diff --git a/composer.json b/composer.json
index 33919186..2fe67da0 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,7 @@
         "clue/http-proxy-react": "^1.8",
         "clue/reactphp-ssh-proxy": "^1.4",
         "clue/socks-react": "^1.4",
-        "phpunit/phpunit": "^9.6 || ^5.7",
+        "phpunit/phpunit": "^9.6 || ^7.5",
         "react/async": "^4 || ^3",
         "react/promise-stream": "^1.4",
         "react/promise-timer": "^1.9"
diff --git a/phpunit.xml.legacy b/phpunit.xml.legacy
index a018d7ab..00868603 100644
--- a/phpunit.xml.legacy
+++ b/phpunit.xml.legacy
@@ -2,7 +2,7 @@
 
 <!-- PHPUnit configuration file with old format for legacy PHPUnit -->
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/5.7/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/7.5/phpunit.xsd"
          bootstrap="vendor/autoload.php"
          colors="true">
     <testsuites>
diff --git a/tests/BrowserTest.php b/tests/BrowserTest.php
index a7188b2c..8f3e10bd 100644
--- a/tests/BrowserTest.php
+++ b/tests/BrowserTest.php
@@ -3,8 +3,11 @@
 namespace React\Tests\Http;
 
 use Psr\Http\Message\RequestInterface;
+use React\EventLoop\LoopInterface;
+use React\Http\Io\Transaction;
 use React\Http\Browser;
 use React\Promise\Promise;
+use React\Socket\ConnectorInterface;
 
 class BrowserTest extends TestCase
 {
@@ -17,8 +20,8 @@ class BrowserTest extends TestCase
      */
     public function setUpBrowser()
     {
-        $this->loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
-        $this->sender = $this->getMockBuilder('React\Http\Io\Transaction')->disableOriginalConstructor()->getMock();
+        $this->loop = $this->createMock(LoopInterface::class);
+        $this->sender = $this->createMock(Transaction::class);
         $this->browser = new Browser(null, $this->loop);
 
         $ref = new \ReflectionProperty($this->browser, 'transaction');
@@ -38,12 +41,12 @@ public function testConstructWithoutLoopAssignsLoopAutomatically()
         $ref->setAccessible(true);
         $loop = $ref->getValue($transaction);
 
-        $this->assertInstanceOf('React\EventLoop\LoopInterface', $loop);
+        $this->assertInstanceOf(LoopInterface::class, $loop);
     }
 
     public function testConstructWithConnectorAssignsGivenConnector()
     {
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
 
         $browser = new Browser($connector);
 
@@ -250,108 +253,106 @@ public function testWithBase()
     {
         $browser = $this->browser->withBase('http://example.com/root');
 
-        $this->assertInstanceOf('React\Http\Browser', $browser);
+        $this->assertInstanceOf(Browser::class, $browser);
         $this->assertNotSame($this->browser, $browser);
     }
 
-    public function provideOtherUris()
-    {
-        return [
-            'empty returns base' => [
-                'http://example.com/base',
-                '',
-                'http://example.com/base',
-            ],
-            'absolute same as base returns base' => [
-                'http://example.com/base',
-                'http://example.com/base',
-                'http://example.com/base',
-            ],
-            'absolute below base returns absolute' => [
-                'http://example.com/base',
-                'http://example.com/base/another',
-                'http://example.com/base/another',
-            ],
-            'slash returns base without path' => [
-                'http://example.com/base',
-                '/',
-                'http://example.com/',
-            ],
-            'relative is added behind base' => [
-                'http://example.com/base/',
-                'test',
-                'http://example.com/base/test',
-            ],
-            'relative is added behind base without path' => [
-                'http://example.com/base',
-                'test',
-                'http://example.com/test',
-            ],
-            'relative level up is added behind parent path' => [
-                'http://example.com/base/foo/',
-                '../bar',
-                'http://example.com/base/bar',
-            ],
-            'absolute with slash is added behind base without path' => [
-                'http://example.com/base',
-                '/test',
-                'http://example.com/test',
-            ],
-            'query string is added behind base' => [
-                'http://example.com/base',
-                '?key=value',
-                'http://example.com/base?key=value',
-            ],
-            'query string is added behind base with slash' => [
-                'http://example.com/base/',
-                '?key=value',
-                'http://example.com/base/?key=value',
-            ],
-            'query string with slash is added behind base without path' => [
-                'http://example.com/base',
-                '/?key=value',
-                'http://example.com/?key=value',
-            ],
-            'absolute with query string below base is returned as-is' => [
-                'http://example.com/base',
-                'http://example.com/base?test',
-                'http://example.com/base?test',
-            ],
-            'urlencoded special chars will stay as-is' => [
-                'http://example.com/%7Bversion%7D/',
-                '',
-                'http://example.com/%7Bversion%7D/'
-            ],
-            'special chars will be urlencoded' => [
-                'http://example.com/{version}/',
-                '',
-                'http://example.com/%7Bversion%7D/'
-            ],
-            'other domain' => [
-                'http://example.com/base/',
-                'http://example.org/base/',
-                'http://example.org/base/'
-            ],
-            'other scheme' => [
-                'http://example.com/base/',
-                'https://example.com/base/',
-                'https://example.com/base/'
-            ],
-            'other port' => [
-                'http://example.com/base/',
-                'http://example.com:81/base/',
-                'http://example.com:81/base/'
-            ],
-            'other path' => [
-                'http://example.com/base/',
-                'http://example.com/other/',
-                'http://example.com/other/'
-            ],
-            'other path due to missing slash' => [
-                'http://example.com/base/',
-                'http://example.com/other',
-                'http://example.com/other'
-            ],
+    public static function provideOtherUris()
+    {
+        yield 'empty returns base' => [
+            'http://example.com/base',
+            '',
+            'http://example.com/base',
+        ];
+        yield 'absolute same as base returns base' => [
+            'http://example.com/base',
+            'http://example.com/base',
+            'http://example.com/base',
+        ];
+        yield 'absolute below base returns absolute' => [
+            'http://example.com/base',
+            'http://example.com/base/another',
+            'http://example.com/base/another',
+        ];
+        yield 'slash returns base without path' => [
+            'http://example.com/base',
+            '/',
+            'http://example.com/',
+        ];
+        yield 'relative is added behind base' => [
+            'http://example.com/base/',
+            'test',
+            'http://example.com/base/test',
+        ];
+        yield 'relative is added behind base without path' => [
+            'http://example.com/base',
+            'test',
+            'http://example.com/test',
+        ];
+        yield 'relative level up is added behind parent path' => [
+            'http://example.com/base/foo/',
+            '../bar',
+            'http://example.com/base/bar',
+        ];
+        yield 'absolute with slash is added behind base without path' => [
+            'http://example.com/base',
+            '/test',
+            'http://example.com/test',
+        ];
+        yield 'query string is added behind base' => [
+            'http://example.com/base',
+            '?key=value',
+            'http://example.com/base?key=value',
+        ];
+        yield 'query string is added behind base with slash' => [
+            'http://example.com/base/',
+            '?key=value',
+            'http://example.com/base/?key=value',
+        ];
+        yield 'query string with slash is added behind base without path' => [
+            'http://example.com/base',
+            '/?key=value',
+            'http://example.com/?key=value',
+        ];
+        yield 'absolute with query string below base is returned as-is' => [
+            'http://example.com/base',
+            'http://example.com/base?test',
+            'http://example.com/base?test',
+        ];
+        yield 'urlencoded special chars will stay as-is' => [
+            'http://example.com/%7Bversion%7D/',
+            '',
+            'http://example.com/%7Bversion%7D/'
+        ];
+        yield 'special chars will be urlencoded' => [
+            'http://example.com/{version}/',
+            '',
+            'http://example.com/%7Bversion%7D/'
+        ];
+        yield 'other domain' => [
+            'http://example.com/base/',
+            'http://example.org/base/',
+            'http://example.org/base/'
+        ];
+        yield 'other scheme' => [
+            'http://example.com/base/',
+            'https://example.com/base/',
+            'https://example.com/base/'
+        ];
+        yield 'other port' => [
+            'http://example.com/base/',
+            'http://example.com:81/base/',
+            'http://example.com:81/base/'
+        ];
+        yield 'other path' => [
+            'http://example.com/base/',
+            'http://example.com/other/',
+            'http://example.com/other/'
+        ];
+        yield 'other path due to missing slash' => [
+            'http://example.com/base/',
+            'http://example.com/other',
+            'http://example.com/other'
         ];
     }
 
@@ -374,13 +375,13 @@ public function testResolveUriWithBaseEndsWithoutSlash($base, $uri, $expectedAbs
 
     public function testWithBaseUrlNotAbsoluteFails()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $this->browser->withBase('hello');
     }
 
     public function testWithBaseUrlInvalidSchemeFails()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $this->browser->withBase('ftp://example.com');
     }
 
@@ -410,7 +411,7 @@ public function testWithProtocolVersionFollowedByGetRequestSendsRequestWithProto
 
     public function testWithProtocolVersionInvalidThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $this->browser->withProtocolVersion('1.2');
     }
 
@@ -418,7 +419,7 @@ public function testCancelGetRequestShouldCancelUnderlyingSocketConnection()
     {
         $pending = new Promise(function () { }, $this->expectCallableOnce());
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('example.com:80')->willReturn($pending);
 
         $this->browser = new Browser($connector, $this->loop);
diff --git a/tests/FunctionalBrowserTest.php b/tests/FunctionalBrowserTest.php
index 92c873d1..d89d92e9 100644
--- a/tests/FunctionalBrowserTest.php
+++ b/tests/FunctionalBrowserTest.php
@@ -176,7 +176,8 @@ public function testGetRequestWithRelativeAddressRejects()
     {
         $promise = $this->browser->get('delay');
 
-        $this->setExpectedException('InvalidArgumentException', 'Invalid request URL given');
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid request URL given');
         await($promise);
     }
 
@@ -201,7 +202,7 @@ public function testCancelGetRequestWillRejectRequest()
         $promise = $this->browser->get($this->base . 'get');
         $promise->cancel();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($promise);
     }
 
@@ -212,13 +213,13 @@ public function testCancelRequestWithPromiseFollowerWillRejectRequest()
         });
         $promise->cancel();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($promise);
     }
 
     public function testRequestWithoutAuthenticationFails()
     {
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($this->browser->get($this->base . 'basic-auth/user/pass'));
     }
 
@@ -269,7 +270,8 @@ public function testCancelRedirectedRequestShouldReject()
             $promise->cancel();
         });
 
-        $this->setExpectedException('RuntimeException', 'Request cancelled');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Request cancelled');
         await($promise);
     }
 
@@ -277,7 +279,8 @@ public function testTimeoutDelayedResponseShouldReject()
     {
         $promise = $this->browser->withTimeout(0.1)->get($this->base . 'delay/10');
 
-        $this->setExpectedException('RuntimeException', 'Request timed out after 0.1 seconds');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Request timed out after 0.1 seconds');
         await($promise);
     }
 
@@ -287,7 +290,8 @@ public function testTimeoutDelayedResponseAfterStreamingRequestShouldReject()
         $promise = $this->browser->withTimeout(0.1)->post($this->base . 'delay/10', [], $stream);
         $stream->end();
 
-        $this->setExpectedException('RuntimeException', 'Request timed out after 0.1 seconds');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Request timed out after 0.1 seconds');
         await($promise);
     }
 
@@ -329,7 +333,7 @@ public function testFollowRedirectsZeroRejectsOnRedirect()
     {
         $browser = $this->browser->withFollowRedirects(0);
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($browser->get($this->base . 'redirect-to?url=get'));
     }
 
@@ -367,11 +371,9 @@ public function testGetRequestWithResponseBufferExceededRejects()
     {
         $promise = $this->browser->withResponseBuffer(4)->get($this->base . 'get');
 
-        $this->setExpectedException(
-            'OverflowException',
-            'Response body size of 5 bytes exceeds maximum of 4 bytes',
-            defined('SOCKET_EMSGSIZE') ? SOCKET_EMSGSIZE : 0
-        );
+        $this->expectException(\OverflowException::class);
+        $this->expectExceptionMessage('Response body size of 5 bytes exceeds maximum of 4 bytes');
+        $this->expectExceptionCode(defined('SOCKET_EMSGSIZE') ? SOCKET_EMSGSIZE : 0);
         await($promise);
     }
 
@@ -379,11 +381,9 @@ public function testGetRequestWithResponseBufferExceededDuringStreamingRejects()
     {
         $promise = $this->browser->withResponseBuffer(4)->get($this->base . 'stream/1');
 
-        $this->setExpectedException(
-            'OverflowException',
-            'Response body size exceeds maximum of 4 bytes',
-            defined('SOCKET_EMSGSIZE') ? SOCKET_EMSGSIZE : 0
-        );
+        $this->expectException(\OverflowException::class);
+        $this->expectExceptionMessage('Response body size exceeds maximum of 4 bytes');
+        $this->expectExceptionCode(defined('SOCKET_EMSGSIZE') ? SOCKET_EMSGSIZE : 0);
         await($promise);
     }
 
@@ -409,7 +409,7 @@ public function testVerifyPeerEnabledForBadSslRejects()
 
         $browser = new Browser($connector);
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($browser->get('https://self-signed.badssl.com/'));
     }
 
@@ -435,7 +435,7 @@ public function testVerifyPeerDisabledForBadSslResolves()
      */
     public function testInvalidPort()
     {
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         await($this->browser->get('http://www.google.com:443/'));
     }
 
@@ -447,7 +447,7 @@ public function testErrorStatusCodeRejectsWithResponseException()
         } catch (ResponseException $e) {
             $this->assertEquals(404, $e->getCode());
 
-            $this->assertInstanceOf('Psr\Http\Message\ResponseInterface', $e->getResponse());
+            $this->assertInstanceOf(ResponseInterface::class, $e->getResponse());
             $this->assertEquals(404, $e->getResponse()->getStatusCode());
         }
     }
@@ -762,7 +762,7 @@ public function testRequestStreamingGetReceivesResponseWithStreamingBodyAndKnown
         $body = $response->getBody();
         $this->assertEquals(5, $body->getSize());
         $this->assertEquals('', (string) $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
     }
 
     public function testRequestStreamingGetReceivesResponseWithStreamingBodyAndUnknownSizeFromStreamingEndpoint()
@@ -773,7 +773,7 @@ public function testRequestStreamingGetReceivesResponseWithStreamingBodyAndUnkno
         $body = $response->getBody();
         $this->assertNull($body->getSize());
         $this->assertEquals('', (string) $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
     }
 
     public function testRequestStreamingGetReceivesStreamingResponseBody()
diff --git a/tests/FunctionalHttpServerTest.php b/tests/FunctionalHttpServerTest.php
index c0fcfe83..dc0bd276 100644
--- a/tests/FunctionalHttpServerTest.php
+++ b/tests/FunctionalHttpServerTest.php
@@ -43,8 +43,8 @@ public function testPlainHttpOnRandomPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://' . noScheme($socket->getAddress()) . '/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://' . noScheme($socket->getAddress()) . '/', $response);
 
         $socket->close();
     }
@@ -70,7 +70,7 @@ function () {
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 404 Not Found", $response);
+        $this->assertStringContainsString("HTTP/1.0 404 Not Found", $response);
 
         $socket->close();
     }
@@ -94,8 +94,8 @@ public function testPlainHttpOnRandomPortWithoutHostHeaderUsesSocketUri()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://' . noScheme($socket->getAddress()) . '/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://' . noScheme($socket->getAddress()) . '/', $response);
 
         $socket->close();
     }
@@ -119,8 +119,8 @@ public function testPlainHttpOnRandomPortWithOtherHostHeaderTakesPrecedence()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://localhost:1000/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://localhost:1000/', $response);
 
         $socket->close();
     }
@@ -150,8 +150,8 @@ public function testSecureHttpsOnRandomPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('https://' . noScheme($socket->getAddress()) . '/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('https://' . noScheme($socket->getAddress()) . '/', $response);
 
         $socket->close();
     }
@@ -181,8 +181,8 @@ public function testSecureHttpsReturnsData()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString("\r\nContent-Length: 33000\r\n", $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString("\r\nContent-Length: 33000\r\n", $response);
         $this->assertStringEndsWith("\r\n". str_repeat('.', 33000), $response);
 
         $socket->close();
@@ -211,8 +211,8 @@ public function testSecureHttpsOnRandomPortWithoutHostHeaderUsesSocketUri()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('https://' . noScheme($socket->getAddress()) . '/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('https://' . noScheme($socket->getAddress()) . '/', $response);
 
         $socket->close();
     }
@@ -240,8 +240,8 @@ public function testPlainHttpOnStandardPortReturnsUriWithNoPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://127.0.0.1/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://127.0.0.1/', $response);
 
         $socket->close();
     }
@@ -269,8 +269,8 @@ public function testPlainHttpOnStandardPortWithoutHostHeaderReturnsUriWithNoPort
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://127.0.0.1/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://127.0.0.1/', $response);
 
         $socket->close();
     }
@@ -303,8 +303,8 @@ public function testSecureHttpsOnStandardPortReturnsUriWithNoPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('https://127.0.0.1/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('https://127.0.0.1/', $response);
 
         $socket->close();
     }
@@ -337,8 +337,8 @@ public function testSecureHttpsOnStandardPortWithoutHostHeaderUsesSocketUri()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('https://127.0.0.1/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('https://127.0.0.1/', $response);
 
         $socket->close();
     }
@@ -366,8 +366,8 @@ public function testPlainHttpOnHttpsStandardPortReturnsUriWithPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('http://127.0.0.1:443/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('http://127.0.0.1:443/', $response);
 
         $socket->close();
     }
@@ -400,8 +400,8 @@ public function testSecureHttpsOnHttpStandardPortReturnsUriWithPort()
 
         $response = await(timeout($result, 1.0));
 
-        $this->assertContainsString("HTTP/1.0 200 OK", $response);
-        $this->assertContainsString('https://127.0.0.1:80/', $response);
+        $this->assertStringContainsString("HTTP/1.0 200 OK", $response);
+        $this->assertStringContainsString('https://127.0.0.1:80/', $response);
 
         $socket->close();
     }
@@ -743,7 +743,7 @@ function (ServerRequestInterface $request) {
         $responses = await(timeout(all($result), 1.0));
 
         foreach ($responses as $response) {
-            $this->assertContainsString("HTTP/1.0 200 OK", $response, $response);
+            $this->assertStringContainsString("HTTP/1.0 200 OK", $response, $response);
             $this->assertTrue(substr($response, -4) == 1024, $response);
         }
 
diff --git a/tests/HttpServerTest.php b/tests/HttpServerTest.php
index fc977d9b..a62e5fbd 100644
--- a/tests/HttpServerTest.php
+++ b/tests/HttpServerTest.php
@@ -4,10 +4,14 @@
 
 use Psr\Http\Message\ServerRequestInterface;
 use React\EventLoop\Loop;
+use React\EventLoop\LoopInterface;
 use React\Http\HttpServer;
 use React\Http\Io\IniUtil;
+use React\Http\Middleware\LimitConcurrentRequestsMiddleware;
+use React\Http\Middleware\RequestBodyBufferMiddleware;
 use React\Http\Middleware\StreamingRequestMiddleware;
 use React\Promise\Deferred;
+use React\Socket\Connection;
 use React\Stream\ReadableStreamInterface;
 use function React\Async\await;
 use function React\Promise\reject;
@@ -25,7 +29,7 @@ final class HttpServerTest extends TestCase
      */
     public function setUpConnectionMockAndSocket()
     {
-        $this->connection = $this->getMockBuilder('React\Socket\Connection')
+        $this->connection = $this->getMockBuilder(Connection::class)
             ->disableOriginalConstructor()
             ->setMethods(
                 [
@@ -65,12 +69,12 @@ public function testConstructWithoutLoopAssignsLoopAutomatically()
         $ref->setAccessible(true);
         $loop = $ref->getValue($clock);
 
-        $this->assertInstanceOf('React\EventLoop\LoopInterface', $loop);
+        $this->assertInstanceOf(LoopInterface::class, $loop);
     }
 
     public function testInvalidCallbackFunctionLeadsToException()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new HttpServer('invalid');
     }
 
@@ -271,8 +275,8 @@ public function testForwardErrors()
         $data = $this->createPostFileUploadRequest();
         $this->connection->emit('data', [implode('', $data)]);
 
-        $this->assertInstanceOf('RuntimeException', $capturedException);
-        $this->assertInstanceOf('Exception', $capturedException->getPrevious());
+        $this->assertInstanceOf(\RuntimeException::class, $capturedException);
+        $this->assertInstanceOf(\Exception::class, $capturedException->getPrevious());
         $this->assertSame($exception, $capturedException->getPrevious());
     }
 
@@ -297,24 +301,22 @@ private function createPostFileUploadRequest()
         return $data;
     }
 
-    public function provideIniSettingsForConcurrency()
+    public static function provideIniSettingsForConcurrency()
     {
-        return [
-            'default settings' => [
-                '128M',
-                '64K', // 8M capped at maximum
-                1024
-            ],
-            'unlimited memory_limit has no concurrency limit' => [
-                '-1',
-                '8M',
-                null
-            ],
-            'small post_max_size results in high concurrency' => [
-                '128M',
-                '1k',
-                65536
-            ]
+        yield 'default settings' => [
+            '128M',
+            '64K', // 8M capped at maximum
+            1024
+        ];
+        yield 'unlimited memory_limit has no concurrency limit' => [
+            '-1',
+            '8M',
+            null
+        ];
+        yield 'small post_max_size results in high concurrency' => [
+            '128M',
+            '1k',
+            65536
         ];
     }
 
@@ -401,7 +403,7 @@ public function testConstructServerWithUnlimitedMemoryLimitDoesNotLimitConcurren
         $middleware = $ref->getValue($middlewareRunner);
 
         $this->assertTrue(is_array($middleware));
-        $this->assertInstanceOf('React\Http\Middleware\RequestBodyBufferMiddleware', $middleware[0]);
+        $this->assertInstanceOf(RequestBodyBufferMiddleware::class, $middleware[0]);
     }
 
     public function testConstructServerWithMemoryLimitDoesLimitConcurrency()
@@ -431,7 +433,7 @@ public function testConstructServerWithMemoryLimitDoesLimitConcurrency()
         $middleware = $ref->getValue($middlewareRunner);
 
         $this->assertTrue(is_array($middleware));
-        $this->assertInstanceOf('React\Http\Middleware\LimitConcurrentRequestsMiddleware', $middleware[0]);
+        $this->assertInstanceOf(LimitConcurrentRequestsMiddleware::class, $middleware[0]);
     }
 
     public function testConstructFiltersOutConfigurationMiddlewareBefore()
diff --git a/tests/Io/AbstractMessageTest.php b/tests/Io/AbstractMessageTest.php
index 59c170ec..5451281a 100644
--- a/tests/Io/AbstractMessageTest.php
+++ b/tests/Io/AbstractMessageTest.php
@@ -26,7 +26,7 @@ public function testWithProtocolVersionReturnsNewInstanceWhenProtocolVersionIsCh
         $message = new MessageMock(
             '1.1',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $new = $message->withProtocolVersion('1.0');
@@ -40,7 +40,7 @@ public function testWithProtocolVersionReturnsSameInstanceWhenProtocolVersionIsU
         $message = new MessageMock(
             '1.1',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $new = $message->withProtocolVersion('1.1');
@@ -55,7 +55,7 @@ public function testHeaderWithStringValue()
             [
                 'Content-Type' => 'text/plain'
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $this->assertEquals(['Content-Type' => ['text/plain']], $message->getHeaders());
@@ -109,7 +109,7 @@ public function testHeaderWithMultipleValues()
                     'b=2'
                 ]
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $this->assertEquals(['Set-Cookie' => ['a=1', 'b=2']], $message->getHeaders());
@@ -152,7 +152,7 @@ public function testHeaderWithEmptyValue()
             [
                 'Content-Type' => []
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $this->assertEquals([], $message->getHeaders());
@@ -183,7 +183,7 @@ public function testHeaderWithMultipleValuesAcrossMixedCaseNamesInConstructorMer
                 'set-cookie' => ['b=2'],
                 'set-COOKIE' => []
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock()
+            $this->createMock(StreamInterface::class)
         );
 
         $this->assertEquals(['set-cookie' => ['a=1', 'b=2']], $message->getHeaders());
@@ -192,14 +192,14 @@ public function testHeaderWithMultipleValuesAcrossMixedCaseNamesInConstructorMer
 
     public function testWithBodyReturnsNewInstanceWhenBodyIsChanged()
     {
-        $body = $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock();
+        $body = $this->createMock(StreamInterface::class);
         $message = new MessageMock(
             '1.1',
             [],
             $body
         );
 
-        $body2 = $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock();
+        $body2 = $this->createMock(StreamInterface::class);
         $new = $message->withBody($body2);
         $this->assertNotSame($message, $new);
         $this->assertSame($body2, $new->getBody());
@@ -208,7 +208,7 @@ public function testWithBodyReturnsNewInstanceWhenBodyIsChanged()
 
     public function testWithBodyReturnsSameInstanceWhenBodyIsUnchanged()
     {
-        $body = $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock();
+        $body = $this->createMock(StreamInterface::class);
         $message = new MessageMock(
             '1.1',
             [],
diff --git a/tests/Io/AbstractRequestTest.php b/tests/Io/AbstractRequestTest.php
index 24990622..5d41369b 100644
--- a/tests/Io/AbstractRequestTest.php
+++ b/tests/Io/AbstractRequestTest.php
@@ -32,12 +32,12 @@ class AbstractRequestTest extends TestCase
 {
     public function testCtorWithInvalidUriThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new RequestMock(
             'GET',
             null,
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
     }
@@ -48,7 +48,7 @@ public function testGetHeadersReturnsHostHeaderFromUri()
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -61,7 +61,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWithCustomHttpPort()
             'GET',
             'http://example.com:8080/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -74,7 +74,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWithCustomPortHttpOnHttpsP
             'GET',
             'http://example.com:443/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -87,7 +87,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWithCustomPortHttpsOnHttpP
             'GET',
             'https://example.com:80/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -100,7 +100,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWithoutDefaultHttpPort()
             'GET',
             'http://example.com:80/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -113,7 +113,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWithoutDefaultHttpsPort()
             'GET',
             'https://example.com:443/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -128,7 +128,7 @@ public function testGetHeadersReturnsHostHeaderFromUriBeforeOtherHeadersExplicit
             [
                 'User-Agent' => 'demo'
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -143,7 +143,7 @@ public function testGetHeadersReturnsHostHeaderFromHeadersExplicitlyGiven()
             [
                 'Host' => 'example.com:8080'
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -158,7 +158,7 @@ public function testGetHeadersReturnsHostHeaderFromUriWhenHeadersExplicitlyGiven
             [
                 'Host' => []
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -171,7 +171,7 @@ public function testGetRequestTargetReturnsPathAndQueryFromUri()
             'GET',
             'http://example.com/demo?name=Alice',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -184,7 +184,7 @@ public function testGetRequestTargetReturnsSlashOnlyIfUriHasNoPathOrQuery()
             'GET',
             'http://example.com',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -197,7 +197,7 @@ public function testGetRequestTargetReturnsRequestTargetInAbsoluteFormIfGivenExp
             'GET',
             'http://example.com/demo?name=Alice',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
         $request = $request->withRequestTarget('http://example.com/demo?name=Alice');
@@ -211,7 +211,7 @@ public function testWithRequestTargetReturnsNewInstanceWhenRequestTargetIsChange
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -227,7 +227,7 @@ public function testWithRequestTargetReturnsSameInstanceWhenRequestTargetIsUncha
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
         $request = $request->withRequestTarget('/');
@@ -243,7 +243,7 @@ public function testWithMethodReturnsNewInstanceWhenMethodIsChanged()
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -259,7 +259,7 @@ public function testWithMethodReturnsSameInstanceWhenMethodIsUnchanged()
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -270,13 +270,13 @@ public function testWithMethodReturnsSameInstanceWhenMethodIsUnchanged()
 
     public function testGetUriReturnsUriInstanceGivenToCtor()
     {
-        $uri = $this->getMockBuilder('Psr\Http\Message\UriInterface')->getMock();
+        $uri = $this->createMock(UriInterface::class);
 
         $request = new RequestMock(
             'GET',
             $uri,
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -289,12 +289,12 @@ public function testGetUriReturnsUriInstanceForUriStringGivenToCtor()
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
         $uri = $request->getUri();
-        $this->assertInstanceOf('Psr\Http\Message\UriInterface', $uri);
+        $this->assertInstanceOf(UriInterface::class, $uri);
         $this->assertEquals('http://example.com/', (string) $uri);
     }
 
@@ -304,11 +304,11 @@ public function testWithUriReturnsNewInstanceWhenUriIsChanged()
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
-        $uri = $this->getMockBuilder('Psr\Http\Message\UriInterface')->getMock();
+        $uri = $this->createMock(UriInterface::class);
         $new = $request->withUri($uri);
 
         $this->assertNotSame($request, $new);
@@ -318,13 +318,13 @@ public function testWithUriReturnsNewInstanceWhenUriIsChanged()
 
     public function testWithUriReturnsSameInstanceWhenUriIsUnchanged()
     {
-        $uri = $this->getMockBuilder('Psr\Http\Message\UriInterface')->getMock();
+        $uri = $this->createMock(UriInterface::class);
 
         $request = new RequestMock(
             'GET',
             $uri,
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -339,7 +339,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderChangedIfUriContainsH
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -357,7 +357,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderChangedIfUriContainsH
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -377,7 +377,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderAddedAsFirstHeaderBef
             [
                 'User-Agent' => 'test'
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
         $request = $request->withoutHeader('Host');
@@ -396,7 +396,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderUnchangedIfUriContain
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -414,7 +414,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderUnchangedIfPreserveHo
             'GET',
             'http://example.com/',
             [],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
 
@@ -434,7 +434,7 @@ public function testWithUriReturnsNewInstanceWithHostHeaderAddedAsFirstHeaderNoM
             [
                 'User-Agent' => 'test'
             ],
-            $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock(),
+            $this->createMock(StreamInterface::class),
             '1.1'
         );
         $request = $request->withoutHeader('Host');
diff --git a/tests/Io/BufferedBodyTest.php b/tests/Io/BufferedBodyTest.php
index 4f5d042a..c8534d50 100644
--- a/tests/Io/BufferedBodyTest.php
+++ b/tests/Io/BufferedBodyTest.php
@@ -91,7 +91,7 @@ public function testSeekBeforeStartThrows()
         } catch (\RuntimeException $e) {
             $this->assertSame(0, $stream->tell());
 
-            $this->setExpectedException('RuntimeException');
+            $this->expectException(\RuntimeException::class);
             throw $e;
         }
     }
@@ -100,7 +100,7 @@ public function testSeekWithInvalidModeThrows()
     {
         $stream = new BufferedBody('hello');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $stream->seek(1, 12345);
     }
 
@@ -109,7 +109,7 @@ public function testSeekAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->seek(0);
     }
 
@@ -118,7 +118,7 @@ public function testTellAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->tell();
     }
 
@@ -136,7 +136,7 @@ public function testRewindAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->rewind();
     }
 
@@ -180,7 +180,7 @@ public function testReadZeroThrows()
     {
         $stream = new BufferedBody('hello');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $stream->read(0);
     }
 
@@ -189,7 +189,7 @@ public function testReadAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->read(10);
     }
 
@@ -218,7 +218,7 @@ public function testGetContentsAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->getContents();
     }
 
@@ -280,7 +280,7 @@ public function testWriteAfterCloseThrows()
         $stream = new BufferedBody('hello');
         $stream->close();
 
-        $this->setExpectedException('RuntimeException');
+        $this->expectException(\RuntimeException::class);
         $stream->write('foo');
     }
 
diff --git a/tests/Io/ChunkedDecoderTest.php b/tests/Io/ChunkedDecoderTest.php
index 5168f2d0..3ae8c742 100644
--- a/tests/Io/ChunkedDecoderTest.php
+++ b/tests/Io/ChunkedDecoderTest.php
@@ -3,7 +3,9 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\ChunkedDecoder;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class ChunkedDecoderTest extends TestCase
@@ -394,7 +396,7 @@ public function testHandleError()
 
     public function testPauseStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $parser = new ChunkedDecoder($input);
@@ -403,7 +405,7 @@ public function testPauseStream()
 
     public function testResumeStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $parser = new ChunkedDecoder($input);
@@ -413,7 +415,7 @@ public function testResumeStream()
 
     public function testPipeStream()
     {
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $this->parser->pipe($dest);
 
diff --git a/tests/Io/ChunkedEncoderTest.php b/tests/Io/ChunkedEncoderTest.php
index 96b97848..cbb3e7ad 100644
--- a/tests/Io/ChunkedEncoderTest.php
+++ b/tests/Io/ChunkedEncoderTest.php
@@ -3,7 +3,9 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\ChunkedEncoder;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class ChunkedEncoderTest extends TestCase
@@ -59,7 +61,7 @@ public function testHandleError()
 
     public function testPauseStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $parser = new ChunkedEncoder($input);
@@ -68,7 +70,7 @@ public function testPauseStream()
 
     public function testResumeStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $parser = new ChunkedEncoder($input);
@@ -78,7 +80,7 @@ public function testResumeStream()
 
     public function testPipeStream()
     {
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $this->chunkedStream->pipe($dest);
 
diff --git a/tests/Io/ClientConnectionManagerTest.php b/tests/Io/ClientConnectionManagerTest.php
index 88c5ff4f..c4b3a07e 100644
--- a/tests/Io/ClientConnectionManagerTest.php
+++ b/tests/Io/ClientConnectionManagerTest.php
@@ -2,10 +2,14 @@
 
 namespace React\Tests\Http\Io;
 
+use React\EventLoop\LoopInterface;
+use React\EventLoop\TimerInterface;
 use React\Http\Io\ClientConnectionManager;
 use React\Http\Message\Uri;
 use React\Promise\Promise;
 use React\Promise\PromiseInterface;
+use React\Socket\ConnectionInterface;
+use React\Socket\ConnectorInterface;
 use React\Tests\Http\TestCase;
 use function React\Promise\resolve;
 
@@ -14,10 +18,10 @@ class ClientConnectionManagerTest extends TestCase
     public function testConnectWithHttpsUriShouldConnectToTlsWithDefaultPort()
     {
         $promise = new Promise(function () { });
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('tls://reactphp.org:443')->willReturn($promise);
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -30,10 +34,10 @@ public function testConnectWithHttpsUriShouldConnectToTlsWithDefaultPort()
     public function testConnectWithHttpUriShouldConnectToTcpWithDefaultPort()
     {
         $promise = new Promise(function () { });
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('reactphp.org:80')->willReturn($promise);
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -44,10 +48,10 @@ public function testConnectWithHttpUriShouldConnectToTcpWithDefaultPort()
     public function testConnectWithExplicitPortShouldConnectWithGivenPort()
     {
         $promise = new Promise(function () { });
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('reactphp.org:8080')->willReturn($promise);
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -57,10 +61,10 @@ public function testConnectWithExplicitPortShouldConnectWithGivenPort()
 
     public function testConnectWithInvalidSchemeShouldRejectWithException()
     {
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->never())->method('connect');
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -71,16 +75,16 @@ public function testConnectWithInvalidSchemeShouldRejectWithException()
             $exception = $reason;
         });
 
-        $this->assertInstanceOf('InvalidArgumentException', $exception);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $exception);
         $this->assertEquals('Invalid request URL given', $exception->getMessage());
     }
 
     public function testConnectWithoutSchemeShouldRejectWithException()
     {
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->never())->method('connect');
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -91,13 +95,13 @@ public function testConnectWithoutSchemeShouldRejectWithException()
             $exception = $reason;
         });
 
-        $this->assertInstanceOf('InvalidArgumentException', $exception);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $exception);
         $this->assertEquals('Invalid request URL given', $exception->getMessage());
     }
 
     public function testConnectReusesIdleConnectionFromPreviousKeepAliveCallWithoutUsingConnectorAndWillAddAndRemoveStreamEventsAndAddAndCancelIdleTimer()
     {
-        $connectionToReuse = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connectionToReuse = $this->createMock(ConnectionInterface::class);
 
         $streamHandler = null;
         $connectionToReuse->expects($this->exactly(3))->method('on')->withConsecutive(
@@ -148,11 +152,11 @@ public function testConnectReusesIdleConnectionFromPreviousKeepAliveCallWithoutU
             ]
         );
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->never())->method('connect');
 
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
@@ -173,13 +177,13 @@ public function testConnectReusesIdleConnectionFromPreviousKeepAliveCallWithoutU
 
     public function testConnectReusesIdleConnectionFromPreviousKeepAliveCallWithoutUsingConnectorAlsoWhenUriPathAndQueryAndFragmentIsDifferent()
     {
-        $connectionToReuse = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connectionToReuse = $this->createMock(ConnectionInterface::class);
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->never())->method('connect');
 
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
@@ -200,13 +204,13 @@ public function testConnectReusesIdleConnectionFromPreviousKeepAliveCallWithoutU
 
     public function testConnectUsesConnectorWithSameUriAndReturnsPromiseForNewConnectionFromConnectorWhenPreviousKeepAliveCallUsedDifferentUri()
     {
-        $connectionToReuse = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connectionToReuse = $this->createMock(ConnectionInterface::class);
 
         $promise = new Promise(function () { });
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('tls://reactphp.org:443')->willReturn($promise);
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
 
@@ -220,14 +224,14 @@ public function testConnectUsesConnectorWithSameUriAndReturnsPromiseForNewConnec
 
     public function testConnectUsesConnectorForNewConnectionWhenPreviousConnectReusedIdleConnectionFromPreviousKeepAliveCall()
     {
-        $firstConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
-        $secondConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $firstConnection = $this->createMock(ConnectionInterface::class);
+        $secondConnection = $this->createMock(ConnectionInterface::class);
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('tls://reactphp.org:443')->willReturn(resolve($secondConnection));
 
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
@@ -251,12 +255,12 @@ public function testConnectUsesConnectorForNewConnectionWhenPreviousConnectReuse
 
     public function testKeepAliveAddsTimerAndDoesNotCloseConnectionImmediately()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->never())->method('close');
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
 
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(0.001, $this->anything());
 
         $connectionManager = new ClientConnectionManager($connector, $loop);
@@ -266,14 +270,14 @@ public function testKeepAliveAddsTimerAndDoesNotCloseConnectionImmediately()
 
     public function testKeepAliveClosesConnectionAfterIdleTimeout()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('close');
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
 
         $timerCallback = null;
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with($this->anything(), $this->callback(function ($cb) use (&$timerCallback) {
             $timerCallback = $cb;
             return true;
@@ -291,18 +295,18 @@ public function testKeepAliveClosesConnectionAfterIdleTimeout()
 
     public function testConnectUsesConnectorForNewConnectionWhenIdleConnectionFromPreviousKeepAliveCallHasAlreadyTimedOut()
     {
-        $firstConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $firstConnection = $this->createMock(ConnectionInterface::class);
         $firstConnection->expects($this->once())->method('close');
 
-        $secondConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $secondConnection = $this->createMock(ConnectionInterface::class);
         $secondConnection->expects($this->never())->method('close');
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('tls://reactphp.org:443')->willReturn(resolve($secondConnection));
 
         $timerCallback = null;
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with($this->anything(), $this->callback(function ($cb) use (&$timerCallback) {
             $timerCallback = $cb;
             return true;
@@ -330,7 +334,7 @@ public function testConnectUsesConnectorForNewConnectionWhenIdleConnectionFromPr
 
     public function testConnectUsesConnectorForNewConnectionWhenIdleConnectionFromPreviousKeepAliveCallHasAlreadyFiredUnexpectedStreamEventBeforeIdleTimeoutThatClosesConnection()
     {
-        $firstConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $firstConnection = $this->createMock(ConnectionInterface::class);
         $firstConnection->expects($this->once())->method('close');
 
         $streamHandler = null;
@@ -358,14 +362,14 @@ public function testConnectUsesConnectorForNewConnectionWhenIdleConnectionFromPr
             ]
         );
 
-        $secondConnection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $secondConnection = $this->createMock(ConnectionInterface::class);
         $secondConnection->expects($this->never())->method('close');
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->with('tls://reactphp.org:443')->willReturn(resolve($secondConnection));
 
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
diff --git a/tests/Io/ClientRequestStreamTest.php b/tests/Io/ClientRequestStreamTest.php
index 0df92961..a20cda61 100644
--- a/tests/Io/ClientRequestStreamTest.php
+++ b/tests/Io/ClientRequestStreamTest.php
@@ -4,11 +4,15 @@
 
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use React\EventLoop\LoopInterface;
+use React\Http\Io\ClientConnectionManager;
 use React\Http\Io\ClientRequestStream;
 use React\Http\Message\Request;
 use React\Http\Message\Uri;
 use React\Promise\Deferred;
 use React\Promise\Promise;
+use React\Socket\Connection;
+use React\Socket\ConnectionInterface;
 use React\Stream\DuplexResourceStream;
 use React\Stream\ReadableStreamInterface;
 use React\Tests\Http\TestCase;
@@ -20,10 +24,10 @@ class ClientRequestStreamTest extends TestCase
     /** @test */
     public function testRequestShouldUseConnectionManagerWithUriFromRequestAndBindToStreamEvents()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
 
         $uri = new Uri('http://www.example.com');
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->with($uri)->willReturn(resolve($connection));
 
         $requestData = new Request('GET', $uri);
@@ -55,13 +59,13 @@ public function testRequestShouldUseConnectionManagerWithUriFromRequestAndBindTo
     /** @test */
     public function requestShouldEmitErrorIfConnectionFails()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(reject(new \RuntimeException()));
 
         $requestData = new Request('GET', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
 
-        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf('RuntimeException')));
+        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf(\RuntimeException::class)));
         $request->on('close', $this->expectCallableOnce());
 
         $request->end();
@@ -70,15 +74,15 @@ public function requestShouldEmitErrorIfConnectionFails()
     /** @test */
     public function requestShouldEmitErrorIfConnectionClosesBeforeResponseIsParsed()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
 
-        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf('RuntimeException')));
+        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf(\RuntimeException::class)));
         $request->on('close', $this->expectCallableOnce());
 
         $request->end();
@@ -88,15 +92,15 @@ public function requestShouldEmitErrorIfConnectionClosesBeforeResponseIsParsed()
     /** @test */
     public function requestShouldEmitErrorIfConnectionEmitsError()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
 
-        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf('Exception')));
+        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class)));
         $request->on('close', $this->expectCallableOnce());
 
         $request->end();
@@ -107,43 +111,41 @@ public static function provideInvalidRequest()
     {
         $request = new Request('GET' , "http://localhost/");
 
-        return [
-            [
-                $request->withMethod("INVA\r\nLID", '')
-            ],
-            [
-                $request->withRequestTarget('/inva lid')
-            ],
-            [
-                $request->withHeader('Invalid', "Yes\r\n")
-            ],
-            [
-                $request->withHeader('Invalid', "Yes\n")
-            ],
-            [
-                $request->withHeader('Invalid', "Yes\r")
-            ],
-            [
-                $request->withHeader("Inva\r\nlid", 'Yes')
-            ],
-            [
-                $request->withHeader("Inva\nlid", 'Yes')
-            ],
-            [
-                $request->withHeader("Inva\rlid", 'Yes')
-            ],
-            [
-                $request->withHeader('Inva Lid', 'Yes')
-            ],
-            [
-                $request->withHeader('Inva:Lid', 'Yes')
-            ],
-            [
-                $request->withHeader('Invalid', "Val\0ue")
-            ],
-            [
-                $request->withHeader("Inva\0lid", 'Yes')
-            ]
+        yield [
+            $request->withMethod("INVA\r\nLID", '')
+        ];
+        yield [
+            $request->withRequestTarget('/inva lid')
+        ];
+        yield [
+            $request->withHeader('Invalid', "Yes\r\n")
+        ];
+        yield [
+            $request->withHeader('Invalid', "Yes\n")
+        ];
+        yield [
+            $request->withHeader('Invalid', "Yes\r")
+        ];
+        yield [
+            $request->withHeader("Inva\r\nlid", 'Yes')
+        ];
+        yield [
+            $request->withHeader("Inva\nlid", 'Yes')
+        ];
+        yield [
+            $request->withHeader("Inva\rlid", 'Yes')
+        ];
+        yield [
+            $request->withHeader('Inva Lid', 'Yes')
+        ];
+        yield [
+            $request->withHeader('Inva:Lid', 'Yes')
+        ];
+        yield [
+            $request->withHeader('Invalid', "Val\0ue")
+        ];
+        yield [
+            $request->withHeader("Inva\0lid", 'Yes')
         ];
     }
 
@@ -153,12 +155,12 @@ public static function provideInvalidRequest()
      */
     public function testStreamShouldEmitErrorBeforeCreatingConnectionWhenRequestIsInvalid(RequestInterface $request)
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->never())->method('connect');
 
         $stream = new ClientRequestStream($connectionManager, $request);
 
-        $stream->on('error', $this->expectCallableOnceWith($this->isInstanceOf('InvalidArgumentException')));
+        $stream->on('error', $this->expectCallableOnceWith($this->isInstanceOf(\InvalidArgumentException::class)));
         $stream->on('close', $this->expectCallableOnce());
 
         $stream->end();
@@ -167,15 +169,15 @@ public function testStreamShouldEmitErrorBeforeCreatingConnectionWhenRequestIsIn
     /** @test */
     public function requestShouldEmitErrorIfRequestParserThrowsException()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
 
-        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf('InvalidArgumentException')));
+        $request->on('error', $this->expectCallableOnceWith($this->isInstanceOf(\InvalidArgumentException::class)));
         $request->on('close', $this->expectCallableOnce());
 
         $request->end();
@@ -185,10 +187,10 @@ public function requestShouldEmitErrorIfRequestParserThrowsException()
     /** @test */
     public function getRequestShouldSendAGetRequest()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.0\r\nHost: www.example.com\r\n\r\n");
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.0');
@@ -200,10 +202,10 @@ public function getRequestShouldSendAGetRequest()
     /** @test */
     public function getHttp11RequestShouldSendAGetRequestWithGivenConnectionCloseHeader()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -215,10 +217,10 @@ public function getHttp11RequestShouldSendAGetRequestWithGivenConnectionCloseHea
     /** @test */
     public function getOptionsAsteriskShouldSendAOptionsRequestAsteriskRequestTarget()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("OPTIONS * HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('OPTIONS', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -230,11 +232,11 @@ public function getOptionsAsteriskShouldSendAOptionsRequestAsteriskRequestTarget
 
     public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsContentLengthZero()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -254,11 +256,11 @@ public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsCon
 
     public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsStatusNoContent()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -278,11 +280,11 @@ public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsSta
 
     public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsStatusNotModifiedWithContentLengthGiven()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -302,11 +304,11 @@ public function testStreamShouldEmitResponseWithEmptyBodyWhenResponseContainsSta
 
     public function testStreamShouldEmitResponseWithEmptyBodyWhenRequestMethodIsHead()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("HEAD / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('HEAD', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -326,11 +328,11 @@ public function testStreamShouldEmitResponseWithEmptyBodyWhenRequestMethodIsHead
 
     public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenResponseContainsContentLengthAndResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -350,11 +352,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenRespons
 
     public function testStreamShouldEmitResponseWithStreamingBodyWithoutDataWhenResponseContainsContentLengthWithoutResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -374,11 +376,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyWithoutDataWhenResp
 
     public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndWhenResponseContainsContentLengthWithIncompleteResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -398,11 +400,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndW
 
     public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenResponseContainsTransferEncodingChunkedAndResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -422,11 +424,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenRespons
 
     public function testStreamShouldEmitResponseWithStreamingBodyWithoutDataWhenResponseContainsTransferEncodingChunkedWithoutResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -446,11 +448,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyWithoutDataWhenResp
 
     public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndWhenResponseContainsTransferEncodingChunkedWithIncompleteResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -470,11 +472,11 @@ public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndW
 
     public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndWhenResponseContainsNoContentLengthAndIncompleteResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -494,7 +496,7 @@ public function testStreamShouldEmitResponseWithStreamingBodyWithDataWithoutEndW
 
     public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenResponseContainsNoContentLengthAndResponseBodyTerminatedByConnectionEndEvent()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n");
         $connection->expects($this->once())->method('close');
 
@@ -510,7 +512,7 @@ public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenRespons
             return true;
         }));
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'close'], '', '1.1');
@@ -533,12 +535,12 @@ public function testStreamShouldEmitResponseWithStreamingBodyUntilEndWhenRespons
 
     public function testStreamShouldReuseConnectionForHttp11ByDefault()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
         $connectionManager->expects($this->once())->method('keepAlive')->with(new Uri('http://www.example.com'), $connection);
 
@@ -554,12 +556,12 @@ public function testStreamShouldReuseConnectionForHttp11ByDefault()
 
     public function testStreamShouldNotReuseConnectionWhenResponseContainsConnectionClose()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.1');
@@ -574,12 +576,12 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsConnection
 
     public function testStreamShouldNotReuseConnectionWhenRequestContainsConnectionCloseWithAdditionalOptions()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: FOO, CLOSE, BAR\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', ['Connection' => 'FOO, CLOSE, BAR'], '', '1.1');
@@ -594,12 +596,12 @@ public function testStreamShouldNotReuseConnectionWhenRequestContainsConnectionC
 
     public function testStreamShouldNotReuseConnectionForHttp10ByDefault()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.0\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.0');
@@ -614,12 +616,12 @@ public function testStreamShouldNotReuseConnectionForHttp10ByDefault()
 
     public function testStreamShouldReuseConnectionForHttp10WhenBothRequestAndResponseContainConnectionKeepAlive()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.0\r\nHost: www.example.com\r\nConnection: keep-alive\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
         $connectionManager->expects($this->once())->method('keepAlive')->with(new Uri('http://www.example.com'), $connection);
 
@@ -635,12 +637,12 @@ public function testStreamShouldReuseConnectionForHttp10WhenBothRequestAndRespon
 
     public function testStreamShouldReuseConnectionForHttp10WhenBothRequestAndResponseContainConnectionKeepAliveWithAdditionalOptions()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.0\r\nHost: www.example.com\r\nConnection: FOO, KEEP-ALIVE, BAR\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
         $connectionManager->expects($this->once())->method('keepAlive')->with(new Uri('http://www.example.com'), $connection);
 
@@ -656,7 +658,7 @@ public function testStreamShouldReuseConnectionForHttp10WhenBothRequestAndRespon
 
     public function testStreamShouldNotReuseConnectionWhenResponseContainsNoContentLengthAndResponseBodyTerminatedByConnectionEndEvent()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(false);
         $connection->expects($this->once())->method('close');
@@ -673,7 +675,7 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsNoContentL
             return true;
         }));
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.1');
@@ -691,7 +693,7 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsNoContentL
 
     public function testStreamShouldNotReuseConnectionWhenResponseContainsContentLengthButIsTerminatedByUnexpectedCloseEvent()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->atMost(1))->method('isReadable')->willReturn(false);
         $connection->expects($this->once())->method('close');
@@ -708,7 +710,7 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsContentLen
             return true;
         }));
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.1');
@@ -726,12 +728,12 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsContentLen
 
     public function testStreamShouldReuseConnectionWhenResponseContainsTransferEncodingChunkedAndResponseBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->once())->method('isReadable')->willReturn(true);
         $connection->expects($this->never())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
         $connectionManager->expects($this->once())->method('keepAlive')->with(new Uri('http://www.example.com'), $connection);
 
@@ -747,12 +749,12 @@ public function testStreamShouldReuseConnectionWhenResponseContainsTransferEncod
 
     public function testStreamShouldNotReuseConnectionWhenResponseContainsTransferEncodingChunkedAndResponseBodyContainsInvalidData()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with("GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n");
         $connection->expects($this->atMost(1))->method('isReadable')->willReturn(true);
         $connection->expects($this->once())->method('close');
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com', [], '', '1.1');
@@ -768,10 +770,10 @@ public function testStreamShouldNotReuseConnectionWhenResponseContainsTransferEn
     /** @test */
     public function postRequestShouldSendAPostRequest()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('write')->with($this->matchesRegularExpression("#^POST / HTTP/1\.0\r\nHost: www.example.com\r\n\r\nsome post data$#"));
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('POST', 'http://www.example.com', [], '', '1.0');
@@ -787,14 +789,14 @@ public function postRequestShouldSendAPostRequest()
     /** @test */
     public function writeWithAPostRequestShouldSendToTheStream()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->exactly(3))->method('write')->withConsecutive(
             [$this->matchesRegularExpression("#^POST / HTTP/1\.0\r\nHost: www.example.com\r\n\r\nsome$#")],
             [$this->identicalTo("post")],
             [$this->identicalTo("data")]
         );
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('POST', 'http://www.example.com', [], '', '1.0');
@@ -812,7 +814,7 @@ public function writeWithAPostRequestShouldSendToTheStream()
     /** @test */
     public function writeWithAPostRequestShouldSendBodyAfterHeadersAndEmitDrainEvent()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->exactly(2))->method('write')->withConsecutive(
             [$this->matchesRegularExpression("#^POST / HTTP/1\.0\r\nHost: www.example.com\r\n\r\nsomepost$#")],
             [$this->identicalTo("data")]
@@ -821,7 +823,7 @@ public function writeWithAPostRequestShouldSendBodyAfterHeadersAndEmitDrainEvent
         );
 
         $deferred = new Deferred();
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn($deferred->promise());
 
         $requestData = new Request('POST', 'http://www.example.com', [], '', '1.0');
@@ -846,7 +848,7 @@ public function writeWithAPostRequestShouldSendBodyAfterHeadersAndEmitDrainEvent
     /** @test */
     public function writeWithAPostRequestShouldForwardDrainEventIfFirstChunkExceedsBuffer()
     {
-        $connection = $this->getMockBuilder('React\Socket\Connection')
+        $connection = $this->getMockBuilder(Connection::class)
             ->disableOriginalConstructor()
             ->setMethods(['write'])
             ->getMock();
@@ -859,7 +861,7 @@ public function writeWithAPostRequestShouldForwardDrainEventIfFirstChunkExceedsB
         );
 
         $deferred = new Deferred();
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn($deferred->promise());
 
         $requestData = new Request('POST', 'http://www.example.com', [], '', '1.0');
@@ -885,22 +887,20 @@ public function writeWithAPostRequestShouldForwardDrainEventIfFirstChunkExceedsB
     /** @test */
     public function pipeShouldPipeDataIntoTheRequestBody()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->exactly(3))->method('write')->withConsecutive(
             [$this->matchesRegularExpression("#^POST / HTTP/1\.0\r\nHost: www.example.com\r\n\r\nsome$#")],
             [$this->identicalTo("post")],
             [$this->identicalTo("data")]
         );
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('POST', 'http://www.example.com', [], '', '1.0');
         $request = new ClientRequestStream($connectionManager, $requestData);
 
-        $loop = $this
-            ->getMockBuilder('React\EventLoop\LoopInterface')
-            ->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $stream = fopen('php://memory', 'r+');
         $stream = new DuplexResourceStream($stream, $loop);
@@ -920,7 +920,7 @@ public function pipeShouldPipeDataIntoTheRequestBody()
      */
     public function writeShouldStartConnecting()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(new Promise(function () { }));
 
         $requestData = new Request('POST', 'http://www.example.com');
@@ -934,7 +934,7 @@ public function writeShouldStartConnecting()
      */
     public function endShouldStartConnectingAndChangeStreamIntoNonWritableMode()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(new Promise(function () { }));
 
         $requestData = new Request('POST', 'http://www.example.com');
@@ -950,7 +950,7 @@ public function endShouldStartConnectingAndChangeStreamIntoNonWritableMode()
      */
     public function closeShouldEmitCloseEvent()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
 
         $requestData = new Request('POST', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
@@ -964,7 +964,7 @@ public function closeShouldEmitCloseEvent()
      */
     public function writeAfterCloseReturnsFalse()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
 
         $requestData = new Request('POST', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
@@ -980,7 +980,7 @@ public function writeAfterCloseReturnsFalse()
      */
     public function endAfterCloseIsNoOp()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->never())->method('connect');
 
         $requestData = new Request('POST', 'http://www.example.com');
@@ -998,7 +998,7 @@ public function closeShouldCancelPendingConnectionAttempt()
         $promise = new Promise(function () {}, function () {
             throw new \RuntimeException();
         });
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn($promise);
 
         $requestData = new Request('POST', 'http://www.example.com');
@@ -1016,7 +1016,7 @@ public function closeShouldCancelPendingConnectionAttempt()
     /** @test */
     public function requestShouldRemoveAllListenerAfterClosed()
     {
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
 
         $requestData = new Request('GET', 'http://www.example.com');
         $request = new ClientRequestStream($connectionManager, $requestData);
@@ -1031,9 +1031,9 @@ public function requestShouldRemoveAllListenerAfterClosed()
     /** @test */
     public function multivalueHeader()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
 
-        $connectionManager = $this->getMockBuilder('React\Http\Io\ClientConnectionManager')->disableOriginalConstructor()->getMock();
+        $connectionManager = $this->createMock(ClientConnectionManager::class);
         $connectionManager->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $requestData = new Request('GET', 'http://www.example.com');
@@ -1054,7 +1054,7 @@ public function multivalueHeader()
         $request->handleData("\r\nbody");
 
         /** @var \Psr\Http\Message\ResponseInterface $response */
-        $this->assertInstanceOf('Psr\Http\Message\ResponseInterface', $response);
+        $this->assertInstanceOf(ResponseInterface::class, $response);
         $this->assertEquals('1.0', $response->getProtocolVersion());
         $this->assertEquals(200, $response->getStatusCode());
         $this->assertEquals('OK', $response->getReasonPhrase());
diff --git a/tests/Io/ClockTest.php b/tests/Io/ClockTest.php
index 8f4b90fa..318fa7ef 100644
--- a/tests/Io/ClockTest.php
+++ b/tests/Io/ClockTest.php
@@ -3,13 +3,14 @@
 namespace React\Tests\Http\Io;
 
 use PHPUnit\Framework\TestCase;
+use React\EventLoop\LoopInterface;
 use React\Http\Io\Clock;
 
 class ClockTest extends TestCase
 {
     public function testNowReturnsSameTimestampMultipleTimesInSameTick()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $clock = new Clock($loop);
 
@@ -21,7 +22,7 @@ public function testNowReturnsSameTimestampMultipleTimesInSameTick()
     public function testNowResetsMemoizedTimestampOnFutureTick()
     {
         $tick = null;
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('futureTick')->with($this->callback(function ($cb) use (&$tick) {
             $tick = $cb;
             return true;
diff --git a/tests/Io/CloseProtectionStreamTest.php b/tests/Io/CloseProtectionStreamTest.php
index 4f3d35ca..f3aa346d 100644
--- a/tests/Io/CloseProtectionStreamTest.php
+++ b/tests/Io/CloseProtectionStreamTest.php
@@ -3,14 +3,16 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\CloseProtectionStream;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class CloseProtectionStreamTest extends TestCase
 {
     public function testCloseDoesNotCloseTheInputStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->disableOriginalConstructor()->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->never())->method('pause');
         $input->expects($this->never())->method('resume');
         $input->expects($this->never())->method('close');
@@ -35,7 +37,7 @@ public function testErrorWontCloseStream()
 
     public function testResumeStreamWillResumeInputStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
         $input->expects($this->once())->method('resume');
 
@@ -46,7 +48,7 @@ public function testResumeStreamWillResumeInputStream()
 
     public function testCloseResumesInputStreamIfItWasPreviouslyPaused()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
         $input->expects($this->once())->method('resume');
 
@@ -73,7 +75,7 @@ public function testPipeStream()
         $input = new ThroughStream();
 
         $protection = new CloseProtectionStream($input);
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $protection->pipe($dest);
 
@@ -132,7 +134,7 @@ public function testEndWontBeEmittedAfterClose()
 
     public function testPauseAfterCloseHasNoEffect()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->never())->method('pause');
         $input->expects($this->never())->method('resume');
 
@@ -146,7 +148,7 @@ public function testPauseAfterCloseHasNoEffect()
 
     public function testResumeAfterCloseHasNoEffect()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->never())->method('pause');
         $input->expects($this->never())->method('resume');
 
diff --git a/tests/Io/EmptyBodyStreamTest.php b/tests/Io/EmptyBodyStreamTest.php
index 3633ff81..4ee92364 100644
--- a/tests/Io/EmptyBodyStreamTest.php
+++ b/tests/Io/EmptyBodyStreamTest.php
@@ -3,6 +3,7 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\EmptyBodyStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class EmptyBodyStreamTest extends TestCase
@@ -36,7 +37,7 @@ public function testResumeIsNoop()
 
     public function testPipeStreamReturnsDestinationStream()
     {
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $this->bodyStream->pipe($dest);
 
@@ -70,13 +71,13 @@ public function testCloseTwiceEmitsCloseEventAndClearsListeners()
 
     public function testTell()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->tell();
     }
 
     public function testEof()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->eof();
     }
 
@@ -87,13 +88,13 @@ public function testIsSeekable()
 
     public function testWrite()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->write('');
     }
 
     public function testRead()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->read(1);
     }
 
@@ -126,13 +127,13 @@ public function testIsReadableReturnsFalseWhenAlreadyClosed()
 
     public function testSeek()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->seek('');
     }
 
     public function testRewind()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->rewind();
     }
 
diff --git a/tests/Io/HttpBodyStreamTest.php b/tests/Io/HttpBodyStreamTest.php
index 1fd269b1..c246bd96 100644
--- a/tests/Io/HttpBodyStreamTest.php
+++ b/tests/Io/HttpBodyStreamTest.php
@@ -3,7 +3,9 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\HttpBodyStream;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class HttpBodyStreamTest extends TestCase
@@ -28,7 +30,7 @@ public function testDataEmit()
 
     public function testPauseStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $bodyStream = new HttpBodyStream($input, null);
@@ -37,7 +39,7 @@ public function testPauseStream()
 
     public function testResumeStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('resume');
 
         $bodyStream = new HttpBodyStream($input, null);
@@ -46,7 +48,7 @@ public function testResumeStream()
 
     public function testPipeStream()
     {
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $this->bodyStream->pipe($dest);
 
@@ -107,13 +109,13 @@ public function testGetSizeCustom()
 
     public function testTell()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->tell();
     }
 
     public function testEof()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->eof();
     }
 
@@ -124,13 +126,13 @@ public function testIsSeekable()
 
     public function testWrite()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->write('');
     }
 
     public function testRead()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->read('');
     }
 
@@ -151,13 +153,13 @@ public function testIsReadable()
 
     public function testSeek()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->seek('');
     }
 
     public function testRewind()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->bodyStream->rewind();
     }
 
diff --git a/tests/Io/IniUtilTest.php b/tests/Io/IniUtilTest.php
index 0bc9a249..2e9f99c9 100644
--- a/tests/Io/IniUtilTest.php
+++ b/tests/Io/IniUtilTest.php
@@ -7,41 +7,39 @@
 
 class IniUtilTest extends TestCase
 {
-    public function provideIniSizes()
+    public static function provideIniSizes()
     {
-        return [
-            [
-                '1',
-                1,
-            ],
-            [
-                '10',
-                10,
-            ],
-            [
-                '1024',
-                1024,
-            ],
-            [
-                '1K',
-                1024,
-            ],
-            [
-                '1.5M',
-                1572864,
-            ],
-            [
-                '64M',
-                67108864,
-            ],
-            [
-                '8G',
-                8589934592,
-            ],
-            [
-                '1T',
-                1099511627776,
-            ],
+        yield [
+            '1',
+            1,
+        ];
+        yield [
+            '10',
+            10,
+        ];
+        yield [
+            '1024',
+            1024,
+        ];
+        yield [
+            '1K',
+            1024,
+        ];
+        yield [
+            '1.5M',
+            1572864,
+        ];
+        yield [
+            '64M',
+            67108864,
+        ];
+        yield [
+            '8G',
+            8589934592,
+        ];
+        yield [
+            '1T',
+            1099511627776,
         ];
     }
 
@@ -58,16 +56,14 @@ public function testIniSizeToBytesWithInvalidSuffixReturnsNumberWithoutSuffix()
         $this->assertEquals('2', IniUtil::iniSizeToBytes('2x'));
     }
 
-    public function provideInvalidInputIniSizeToBytes()
+    public static function provideInvalidInputIniSizeToBytes()
     {
-        return [
-            ['-1G'],
-            ['0G'],
-            ['foo'],
-            ['fooK'],
-            ['1ooL'],
-            ['1ooL'],
-        ];
+        yield ['-1G'];
+        yield ['0G'];
+        yield ['foo'];
+        yield ['fooK'];
+        yield ['1ooL'];
+        yield ['1ooL'];
     }
 
     /**
@@ -75,7 +71,7 @@ public function provideInvalidInputIniSizeToBytes()
      */
     public function testInvalidInputIniSizeToBytes($input)
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         IniUtil::iniSizeToBytes($input);
     }
 }
diff --git a/tests/Io/LengthLimitedStreamTest.php b/tests/Io/LengthLimitedStreamTest.php
index f1761a0b..b841257a 100644
--- a/tests/Io/LengthLimitedStreamTest.php
+++ b/tests/Io/LengthLimitedStreamTest.php
@@ -3,7 +3,9 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\LengthLimitedStream;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Stream\WritableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class LengthLimitedStreamTest extends TestCase
@@ -59,7 +61,7 @@ public function testHandleError()
 
     public function testPauseStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $stream = new LengthLimitedStream($input, 0);
@@ -68,7 +70,7 @@ public function testPauseStream()
 
     public function testResumeStream()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $stream = new LengthLimitedStream($input, 0);
@@ -79,7 +81,7 @@ public function testResumeStream()
     public function testPipeStream()
     {
         $stream = new LengthLimitedStream($this->input, 0);
-        $dest = $this->getMockBuilder('React\Stream\WritableStreamInterface')->getMock();
+        $dest = $this->createMock(WritableStreamInterface::class);
 
         $ret = $stream->pipe($dest);
 
diff --git a/tests/Io/MiddlewareRunnerTest.php b/tests/Io/MiddlewareRunnerTest.php
index e46039bf..a2344d3a 100644
--- a/tests/Io/MiddlewareRunnerTest.php
+++ b/tests/Io/MiddlewareRunnerTest.php
@@ -23,7 +23,8 @@ public function testEmptyMiddlewareStackThrowsException()
         $middlewares = [];
         $middlewareStack = new MiddlewareRunner($middlewares);
 
-        $this->setExpectedException('RuntimeException', 'No middleware to run');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('No middleware to run');
         $middlewareStack($request);
     }
 
@@ -74,7 +75,8 @@ function (ServerRequestInterface $request) {
 
         $request = new ServerRequest('GET', 'http://example.com/');
 
-        $this->setExpectedException('RuntimeException', 'hello');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('hello');
         $middleware($request);
     }
 
@@ -88,11 +90,12 @@ function (ServerRequestInterface $request) {
 
         $request = new ServerRequest('GET', 'http://example.com/');
 
-        $this->setExpectedException('Throwable', 'hello');
+        $this->expectException(\Throwable::class);
+        $this->expectExceptionMessage('hello');
         $middleware($request);
     }
 
-    public function provideProcessStackMiddlewares()
+    public static function provideProcessStackMiddlewares()
     {
         $processStackA = new ProcessStack();
         $processStackB = new ProcessStack();
@@ -101,41 +104,39 @@ public function provideProcessStackMiddlewares()
         $responseMiddleware = function () {
             return new Response(200);
         };
-        return [
+        yield [
             [
-                [
-                    $processStackA,
-                    $responseMiddleware,
-                ],
-                1,
+                $processStackA,
+                $responseMiddleware,
             ],
+            1,
+        ];
+        yield [
             [
-                [
-                    $processStackB,
-                    $processStackB,
-                    $responseMiddleware,
-                ],
-                2,
+                $processStackB,
+                $processStackB,
+                $responseMiddleware,
             ],
+            2,
+        ];
+        yield [
             [
-                [
-                    $processStackC,
-                    $processStackC,
-                    $processStackC,
-                    $responseMiddleware,
-                ],
-                3,
+                $processStackC,
+                $processStackC,
+                $processStackC,
+                $responseMiddleware,
             ],
+            3,
+        ];
+        yield [
             [
-                [
-                    $processStackD,
-                    $processStackD,
-                    $processStackD,
-                    $processStackD,
-                    $responseMiddleware,
-                ],
-                4,
+                $processStackD,
+                $processStackD,
+                $processStackD,
+                $processStackD,
+                $responseMiddleware,
             ],
+            4,
         ];
     }
 
@@ -172,19 +173,17 @@ public function testProcessStack(array $middlewares, $expectedCallCount)
         }
     }
 
-    public function provideErrorHandler()
+    public static function provideErrorHandler()
     {
-        return [
-            [
-                function (\Exception $e) {
-                    throw $e;
-                }
-            ],
-            [
-                function (\Exception $e) {
-                    return reject($e);
-                }
-            ]
+        yield [
+            function (\Exception $e) {
+                throw $e;
+            }
+        ];
+        yield [
+            function (\Exception $e) {
+                return reject($e);
+            }
         ];
     }
 
@@ -193,7 +192,7 @@ function (\Exception $e) {
      */
     public function testNextCanBeRunMoreThanOnceWithoutCorruptingTheMiddlewareStack($errorHandler)
     {
-        $exception = new \RuntimeException('exception');
+        $exception = new \RuntimeException(\exception::class);
         $retryCalled = 0;
         $error = null;
         $retry = function ($request, $next) use (&$error, &$retryCalled) {
@@ -276,129 +275,127 @@ function (ServerRequestInterface $request) use (&$receivedRequests) {
         );
     }
 
-    public function provideUncommonMiddlewareArrayFormats()
+    public static function provideUncommonMiddlewareArrayFormats()
     {
-        return [
-            [
-                function () {
-                    $sequence = '';
-
-                    // Numeric index gap
-                    return [
-                        0 => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'A';
-
-                            return $next($request);
-                        },
-                        2 => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'B';
-
-                            return $next($request);
-                        },
-                        3 => function () use (&$sequence) {
-                            return new Response(200, [], $sequence . 'C');
-                        },
-                    ];
-                },
-                'ABC',
-            ],
-            [
-                function () {
-                    $sequence = '';
-
-                    // Reversed numeric indexes
-                    return [
-                        2 => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'A';
-
-                            return $next($request);
-                        },
-                        1 => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'B';
-
-                            return $next($request);
-                        },
-                        0 => function () use (&$sequence) {
-                            return new Response(200, [], $sequence . 'C');
-                        },
-                    ];
-                },
-                'ABC',
-            ],
-            [
-                function () {
-                    $sequence = '';
-
-                    // Associative array
-                    return [
-                        'middleware1' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'A';
-
-                            return $next($request);
-                        },
-                        'middleware2' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'B';
-
-                            return $next($request);
-                        },
-                        'middleware3' => function () use (&$sequence) {
-                            return new Response(200, [], $sequence . 'C');
-                        },
-                    ];
-                },
-                'ABC',
-            ],
-            [
-                function () {
-                    $sequence = '';
-
-                    // Associative array with empty or trimmable string keys
-                    return [
-                        '' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'A';
-
-                            return $next($request);
-                        },
-                        ' ' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'B';
-
-                            return $next($request);
-                        },
-                        '  ' => function () use (&$sequence) {
-                            return new Response(200, [], $sequence . 'C');
-                        },
-                    ];
-                },
-                'ABC',
-            ],
-            [
-                function () {
-                    $sequence = '';
-
-                    // Mixed array keys
-                    return [
-                        '' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'A';
-
-                            return $next($request);
-                        },
-                        0 => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'B';
-
-                            return $next($request);
-                        },
-                        'foo' => function (ServerRequestInterface $request, $next) use (&$sequence) {
-                            $sequence .= 'C';
-
-                            return $next($request);
-                        },
-                        2 => function () use (&$sequence) {
-                            return new Response(200, [], $sequence . 'D');
-                        },
-                    ];
-                },
-                'ABCD',
-            ],
+        yield [
+            function () {
+                $sequence = '';
+
+                // Numeric index gap
+                return [
+                    0 => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'A';
+
+                        return $next($request);
+                    },
+                    2 => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'B';
+
+                        return $next($request);
+                    },
+                    3 => function () use (&$sequence) {
+                        return new Response(200, [], $sequence . 'C');
+                    },
+                ];
+            },
+            'ABC',
+        ];
+        yield [
+            function () {
+                $sequence = '';
+
+                // Reversed numeric indexes
+                return [
+                    2 => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'A';
+
+                        return $next($request);
+                    },
+                    1 => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'B';
+
+                        return $next($request);
+                    },
+                    0 => function () use (&$sequence) {
+                        return new Response(200, [], $sequence . 'C');
+                    },
+                ];
+            },
+            'ABC',
+        ];
+        yield [
+            function () {
+                $sequence = '';
+
+                // Associative array
+                return [
+                    'middleware1' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'A';
+
+                        return $next($request);
+                    },
+                    'middleware2' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'B';
+
+                        return $next($request);
+                    },
+                    'middleware3' => function () use (&$sequence) {
+                        return new Response(200, [], $sequence . 'C');
+                    },
+                ];
+            },
+            'ABC',
+        ];
+        yield [
+            function () {
+                $sequence = '';
+
+                // Associative array with empty or trimmable string keys
+                return [
+                    '' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'A';
+
+                        return $next($request);
+                    },
+                    ' ' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'B';
+
+                        return $next($request);
+                    },
+                    '  ' => function () use (&$sequence) {
+                        return new Response(200, [], $sequence . 'C');
+                    },
+                ];
+            },
+            'ABC',
+        ];
+        yield [
+            function () {
+                $sequence = '';
+
+                // Mixed array keys
+                return [
+                    '' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'A';
+
+                        return $next($request);
+                    },
+                    0 => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'B';
+
+                        return $next($request);
+                    },
+                    'foo' => function (ServerRequestInterface $request, $next) use (&$sequence) {
+                        $sequence .= 'C';
+
+                        return $next($request);
+                    },
+                    2 => function () use (&$sequence) {
+                        return new Response(200, [], $sequence . 'D');
+                    },
+                ];
+            },
+            'ABCD',
         ];
     }
 
diff --git a/tests/Io/MultipartParserTest.php b/tests/Io/MultipartParserTest.php
index ba439760..ebc5972f 100644
--- a/tests/Io/MultipartParserTest.php
+++ b/tests/Io/MultipartParserTest.php
@@ -2,6 +2,7 @@
 
 namespace React\Tests\Http\Io\Middleware;
 
+use Psr\Http\Message\UploadedFileInterface;
 use React\Http\Io\MultipartParser;
 use React\Http\Message\ServerRequest;
 use React\Tests\Http\TestCase;
@@ -673,7 +674,7 @@ public function testInvalidUploadFileWithoutContentTypeUsesNullValue()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -708,7 +709,7 @@ public function testInvalidUploadFileWithoutMultipleContentTypeUsesLastValue()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -742,7 +743,7 @@ public function testUploadEmptyFile()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -776,7 +777,7 @@ public function testUploadTooLargeFile()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -809,7 +810,7 @@ public function testUploadTooLargeFileWithIniLikeSize()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -842,7 +843,7 @@ public function testUploadNoFile()
 
         $this->assertCount(1, $files);
         $this->assertTrue(isset($files['file']));
-        $this->assertInstanceOf('Psr\Http\Message\UploadedFileInterface', $files['file']);
+        $this->assertInstanceOf(UploadedFileInterface::class, $files['file']);
 
         /* @var $file \Psr\Http\Message\UploadedFileInterface */
         $file = $files['file'];
@@ -1046,7 +1047,7 @@ public function testWeOnlyParseTheAmountOfMultiPartChunksWeConfigured()
 
         $parser = new MultipartParser();
 
-        $reflectecClass = new \ReflectionClass('\React\Http\Io\MultipartParser');
+        $reflectecClass = new \ReflectionClass(MultipartParser::class);
         $requestProperty = $reflectecClass->getProperty('request');
         $requestProperty->setAccessible(true);
         $cursorProperty = $reflectecClass->getProperty('cursor');
diff --git a/tests/Io/PauseBufferStreamTest.php b/tests/Io/PauseBufferStreamTest.php
index 05bf3ee3..139db8fd 100644
--- a/tests/Io/PauseBufferStreamTest.php
+++ b/tests/Io/PauseBufferStreamTest.php
@@ -2,15 +2,16 @@
 
 namespace React\Tests\Io;
 
-use React\Tests\Http\TestCase;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Tests\Http\TestCase;
 use React\Http\Io\PauseBufferStream;
 
 class PauseBufferStreamTest extends TestCase
 {
     public function testPauseMethodWillBePassedThroughToInput()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('pause');
 
         $stream = new PauseBufferStream($input);
@@ -19,7 +20,7 @@ public function testPauseMethodWillBePassedThroughToInput()
 
     public function testCloseMethodWillBePassedThroughToInput()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->once())->method('close');
 
         $stream = new PauseBufferStream($input);
@@ -28,7 +29,7 @@ public function testCloseMethodWillBePassedThroughToInput()
 
     public function testPauseMethodWillNotBePassedThroughToInputAfterClose()
     {
-        $input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $input = $this->createMock(ReadableStreamInterface::class);
         $input->expects($this->never())->method('pause');
 
         $stream = new PauseBufferStream($input);
diff --git a/tests/Io/ReadableBodyStreamTest.php b/tests/Io/ReadableBodyStreamTest.php
index 8ece6791..2409a6be 100644
--- a/tests/Io/ReadableBodyStreamTest.php
+++ b/tests/Io/ReadableBodyStreamTest.php
@@ -3,8 +3,9 @@
 namespace React\Tests\Http\Io;
 
 use React\Http\Io\ReadableBodyStream;
-use React\Tests\Http\TestCase;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
+use React\Tests\Http\TestCase;
 
 class ReadableBodyStreamTest extends TestCase
 {
@@ -16,7 +17,7 @@ class ReadableBodyStreamTest extends TestCase
      */
     public function setUpStream()
     {
-        $this->input = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $this->input = $this->createMock(ReadableStreamInterface::class);
         $this->stream = new ReadableBodyStream($this->input);
     }
 
@@ -102,7 +103,7 @@ public function testEndInputWillEmitErrorEventWhenDataDoesNotReachExpectedLength
         $this->input->write('hi');
         $this->input->end();
 
-        $this->assertInstanceOf('UnderflowException', $called);
+        $this->assertInstanceOf(\UnderflowException::class, $called);
         $this->assertSame('Unexpected end of response body after 2/5 bytes', $called->getMessage());
     }
 
@@ -188,7 +189,7 @@ public function testPointlessTostringReturnsEmptyString()
 
     public function testPointlessDetachThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->detach();
     }
 
@@ -199,7 +200,7 @@ public function testPointlessGetSizeReturnsNull()
 
     public function testPointlessTellThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->tell();
     }
 
@@ -210,13 +211,13 @@ public function testPointlessIsSeekableReturnsFalse()
 
     public function testPointlessSeekThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->seek(0);
     }
 
     public function testPointlessRewindThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->rewind();
     }
 
@@ -227,19 +228,19 @@ public function testPointlessIsWritableReturnsFalse()
 
     public function testPointlessWriteThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->write('');
     }
 
     public function testPointlessReadThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->read(8192);
     }
 
     public function testPointlessGetContentsThrows()
     {
-        $this->setExpectedException('BadMethodCallException');
+        $this->expectException(\BadMethodCallException::class);
         $this->stream->getContents();
     }
 
diff --git a/tests/Io/RequestHeaderParserTest.php b/tests/Io/RequestHeaderParserTest.php
index d15d4e7f..568fc375 100644
--- a/tests/Io/RequestHeaderParserTest.php
+++ b/tests/Io/RequestHeaderParserTest.php
@@ -2,20 +2,24 @@
 
 namespace React\Tests\Http\Io;
 
+use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ServerRequestInterface;
+use React\Http\Io\Clock;
 use React\Http\Io\RequestHeaderParser;
+use React\Socket\Connection;
+use React\Stream\ReadableStreamInterface;
 use React\Tests\Http\TestCase;
 
 class RequestHeaderParserTest extends TestCase
 {
     public function testSplitShouldHappenOnDoubleCrlf()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
 
         $parser->handle($connection);
 
@@ -31,12 +35,12 @@ public function testSplitShouldHappenOnDoubleCrlf()
 
     public function testFeedInOneGo()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableOnce());
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = $this->createGetRequest();
@@ -45,7 +49,7 @@ public function testFeedInOneGo()
 
     public function testFeedTwoRequestsOnSeparateConnections()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
@@ -54,8 +58,8 @@ public function testFeedTwoRequestsOnSeparateConnections()
             ++$called;
         });
 
-        $connection1 = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
-        $connection2 = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection1 = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection2 = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection1);
         $parser->handle($connection2);
 
@@ -71,7 +75,7 @@ public function testHeadersEventShouldEmitRequestAndConnection()
         $request = null;
         $conn = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', function ($parsedRequest, $connection) use (&$request, &$conn) {
@@ -79,13 +83,13 @@ public function testHeadersEventShouldEmitRequestAndConnection()
             $conn = $connection;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = $this->createGetRequest();
         $connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\RequestInterface', $request);
+        $this->assertInstanceOf(RequestInterface::class, $request);
         $this->assertSame('GET', $request->getMethod());
         $this->assertEquals('http://example.com/', $request->getUri());
         $this->assertSame('1.1', $request->getProtocolVersion());
@@ -96,21 +100,21 @@ public function testHeadersEventShouldEmitRequestAndConnection()
 
     public function testHeadersEventShouldEmitRequestWhichShouldEmitEndForStreamingBodyWithoutContentLengthFromInitialRequestBody()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
         $ended = false;
         $parser->on('headers', function (ServerRequestInterface $request) use (&$ended) {
             $body = $request->getBody();
-            $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+            $this->assertInstanceOf(ReadableStreamInterface::class, $body);
 
             $body->on('end', function () use (&$ended) {
                 $ended = true;
             });
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = "GET / HTTP/1.0\r\n\r\n";
@@ -121,14 +125,14 @@ public function testHeadersEventShouldEmitRequestWhichShouldEmitEndForStreamingB
 
     public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyDataFromInitialRequestBody()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
         $buffer = '';
         $parser->on('headers', function (ServerRequestInterface $request) use (&$buffer) {
             $body = $request->getBody();
-            $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+            $this->assertInstanceOf(ReadableStreamInterface::class, $body);
 
             $body->on('data', function ($chunk) use (&$buffer) {
                 $buffer .= $chunk;
@@ -138,7 +142,7 @@ public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyDat
             });
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = "POST / HTTP/1.0\r\nContent-Length: 11\r\n\r\n";
@@ -150,21 +154,21 @@ public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyDat
 
     public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyWithPlentyOfDataFromInitialRequestBody()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
         $buffer = '';
         $parser->on('headers', function (ServerRequestInterface $request) use (&$buffer) {
             $body = $request->getBody();
-            $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+            $this->assertInstanceOf(ReadableStreamInterface::class, $body);
 
             $body->on('data', function ($chunk) use (&$buffer) {
                 $buffer .= $chunk;
             });
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $size = 10000;
@@ -177,21 +181,21 @@ public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyWit
 
     public function testHeadersEventShouldEmitRequestWhichShouldNotEmitStreamingBodyDataWithoutContentLengthFromInitialRequestBody()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
         $buffer = '';
         $parser->on('headers', function (ServerRequestInterface $request) use (&$buffer) {
             $body = $request->getBody();
-            $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+            $this->assertInstanceOf(ReadableStreamInterface::class, $body);
 
             $body->on('data', function ($chunk) use (&$buffer) {
                 $buffer .= $chunk;
             });
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = "POST / HTTP/1.0\r\n\r\n";
@@ -203,21 +207,21 @@ public function testHeadersEventShouldEmitRequestWhichShouldNotEmitStreamingBody
 
     public function testHeadersEventShouldEmitRequestWhichShouldEmitStreamingBodyDataUntilContentLengthBoundaryFromInitialRequestBody()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
         $buffer = '';
         $parser->on('headers', function (ServerRequestInterface $request) use (&$buffer) {
             $body = $request->getBody();
-            $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+            $this->assertInstanceOf(ReadableStreamInterface::class, $body);
 
             $body->on('data', function ($chunk) use (&$buffer) {
                 $buffer .= $chunk;
             });
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = "POST / HTTP/1.0\r\nContent-Length: 6\r\n\r\n";
@@ -231,20 +235,20 @@ public function testHeadersEventShouldParsePathAndQueryString()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', function ($parsedRequest) use (&$request) {
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = $this->createAdvancedPostRequest();
         $connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\RequestInterface', $request);
+        $this->assertInstanceOf(RequestInterface::class, $request);
         $this->assertSame('POST', $request->getMethod());
         $this->assertEquals('http://example.com/foo?bar=baz', $request->getUri());
         $this->assertSame('1.1', $request->getProtocolVersion());
@@ -260,14 +264,14 @@ public function testHeaderEventWithShouldApplyDefaultAddressFromLocalConnectionA
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', function ($parsedRequest) use (&$request) {
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('tcp://127.1.1.1:8000');
         $parser->handle($connection);
 
@@ -281,14 +285,14 @@ public function testHeaderEventViaHttpsShouldApplyHttpsSchemeFromLocalTlsConnect
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', function ($parsedRequest) use (&$request) {
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('tls://127.1.1.1:8000');
         $parser->handle($connection);
 
@@ -303,7 +307,7 @@ public function testHeaderOverflowShouldEmitError()
         $error = null;
         $passedConnection = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -312,13 +316,13 @@ public function testHeaderOverflowShouldEmitError()
             $passedConnection = $connection;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $data = str_repeat('A', 8193);
         $connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('OverflowException', $error);
+        $this->assertInstanceOf(\OverflowException::class, $error);
         $this->assertSame('Maximum header size of 8192 exceeded.', $error->getMessage());
         $this->assertSame($connection, $passedConnection);
     }
@@ -327,7 +331,7 @@ public function testInvalidEmptyRequestHeadersParseException()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -335,12 +339,12 @@ public function testInvalidEmptyRequestHeadersParseException()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Unable to parse invalid request-line', $error->getMessage());
     }
 
@@ -348,7 +352,7 @@ public function testInvalidMalformedRequestLineParseException()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -356,12 +360,12 @@ public function testInvalidMalformedRequestLineParseException()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET /\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Unable to parse invalid request-line', $error->getMessage());
     }
 
@@ -369,7 +373,7 @@ public function testInvalidMalformedRequestHeadersThrowsParseException()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -377,12 +381,12 @@ public function testInvalidMalformedRequestHeadersThrowsParseException()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost : yes\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Unable to parse invalid request header fields', $error->getMessage());
     }
 
@@ -390,7 +394,7 @@ public function testInvalidMalformedRequestHeadersWhitespaceThrowsParseException
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -398,12 +402,12 @@ public function testInvalidMalformedRequestHeadersWhitespaceThrowsParseException
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: yes\rFoo: bar\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Unable to parse invalid request header fields', $error->getMessage());
     }
 
@@ -411,7 +415,7 @@ public function testInvalidAbsoluteFormSchemeEmitsError()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -419,12 +423,12 @@ public function testInvalidAbsoluteFormSchemeEmitsError()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET tcp://example.com:80/ HTTP/1.0\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Invalid absolute-form request-target', $error->getMessage());
     }
 
@@ -432,7 +436,7 @@ public function testOriginFormWithSchemeSeparatorInParam()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('error', $this->expectCallableNever());
@@ -440,12 +444,12 @@ public function testOriginFormWithSchemeSeparatorInParam()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET /somepath?param=http://example.com HTTP/1.1\r\nHost: localhost\r\n\r\n"]);
 
-        $this->assertInstanceOf('Psr\Http\Message\RequestInterface', $request);
+        $this->assertInstanceOf(RequestInterface::class, $request);
         $this->assertSame('GET', $request->getMethod());
         $this->assertEquals('http://localhost/somepath?param=http://example.com', $request->getUri());
         $this->assertSame('1.1', $request->getProtocolVersion());
@@ -459,7 +463,7 @@ public function testUriStartingWithColonSlashSlashFails()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -467,12 +471,12 @@ public function testUriStartingWithColonSlashSlashFails()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET ://example.com:80/ HTTP/1.0\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Invalid absolute-form request-target', $error->getMessage());
     }
 
@@ -480,7 +484,7 @@ public function testInvalidAbsoluteFormWithFragmentEmitsError()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -488,12 +492,12 @@ public function testInvalidAbsoluteFormWithFragmentEmitsError()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET http://example.com:80/#home HTTP/1.0\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Invalid absolute-form request-target', $error->getMessage());
     }
 
@@ -501,7 +505,7 @@ public function testInvalidHeaderContainsFullUri()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -509,12 +513,12 @@ public function testInvalidHeaderContainsFullUri()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: http://user:pass@host/\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Invalid Host header value', $error->getMessage());
     }
 
@@ -522,7 +526,7 @@ public function testInvalidAbsoluteFormWithHostHeaderEmpty()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -530,12 +534,12 @@ public function testInvalidAbsoluteFormWithHostHeaderEmpty()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET http://example.com/ HTTP/1.1\r\nHost: \r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('Invalid Host header value', $error->getMessage());
     }
 
@@ -543,7 +547,7 @@ public function testInvalidConnectRequestWithNonAuthorityForm()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -551,12 +555,12 @@ public function testInvalidConnectRequestWithNonAuthorityForm()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["CONNECT http://example.com:8080/ HTTP/1.1\r\nHost: example.com:8080\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame('CONNECT method MUST use authority-form request target', $error->getMessage());
     }
 
@@ -564,7 +568,7 @@ public function testInvalidHttpVersion()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -572,12 +576,12 @@ public function testInvalidHttpVersion()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.2\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame(505, $error->getCode());
         $this->assertSame('Received request with invalid protocol version', $error->getMessage());
     }
@@ -586,7 +590,7 @@ public function testInvalidContentLengthRequestHeaderWillEmitError()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -594,12 +598,12 @@ public function testInvalidContentLengthRequestHeaderWillEmitError()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: localhost\r\nContent-Length: foo\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame(400, $error->getCode());
         $this->assertSame('The value of `Content-Length` is not valid', $error->getMessage());
     }
@@ -608,7 +612,7 @@ public function testInvalidRequestWithMultipleContentLengthRequestHeadersWillEmi
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -616,12 +620,12 @@ public function testInvalidRequestWithMultipleContentLengthRequestHeadersWillEmi
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: localhost\r\nContent-Length: 4\r\nContent-Length: 5\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame(400, $error->getCode());
         $this->assertSame('The value of `Content-Length` is not valid', $error->getMessage());
     }
@@ -630,7 +634,7 @@ public function testInvalidTransferEncodingRequestHeaderWillEmitError()
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -638,12 +642,12 @@ public function testInvalidTransferEncodingRequestHeaderWillEmitError()
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: localhost\r\nTransfer-Encoding: foo\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame(501, $error->getCode());
         $this->assertSame('Only chunked-encoding is allowed for Transfer-Encoding', $error->getMessage());
     }
@@ -652,7 +656,7 @@ public function testInvalidRequestWithBothTransferEncodingAndContentLengthWillEm
     {
         $error = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
         $parser->on('headers', $this->expectCallableNever());
@@ -660,12 +664,12 @@ public function testInvalidRequestWithBothTransferEncodingAndContentLengthWillEm
             $error = $message;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET / HTTP/1.1\r\nHost: localhost\r\nTransfer-Encoding: chunked\r\nContent-Length: 0\r\n\r\n"]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
         $this->assertSame(400, $error->getCode());
         $this->assertSame('Using both `Transfer-Encoding: chunked` and `Content-Length` is not allowed', $error->getMessage());
     }
@@ -674,7 +678,7 @@ public function testServerParamsWillBeSetOnHttpsRequest()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
         $clock->expects($this->once())->method('now')->willReturn(1652972091.3958);
 
         $parser = new RequestHeaderParser($clock);
@@ -683,7 +687,7 @@ public function testServerParamsWillBeSetOnHttpsRequest()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('tls://127.1.1.1:8000');
         $connection->expects($this->once())->method('getRemoteAddress')->willReturn('tls://192.168.1.1:8001');
         $parser->handle($connection);
@@ -707,7 +711,7 @@ public function testServerParamsWillBeSetOnHttpRequest()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
         $clock->expects($this->once())->method('now')->willReturn(1652972091.3958);
 
         $parser = new RequestHeaderParser($clock);
@@ -716,7 +720,7 @@ public function testServerParamsWillBeSetOnHttpRequest()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('tcp://127.1.1.1:8000');
         $connection->expects($this->once())->method('getRemoteAddress')->willReturn('tcp://192.168.1.1:8001');
         $parser->handle($connection);
@@ -740,7 +744,7 @@ public function testServerParamsWillNotSetRemoteAddressForUnixDomainSockets()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
         $clock->expects($this->once())->method('now')->willReturn(1652972091.3958);
 
         $parser = new RequestHeaderParser($clock);
@@ -749,7 +753,7 @@ public function testServerParamsWillNotSetRemoteAddressForUnixDomainSockets()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('unix://./server.sock');
         $connection->expects($this->once())->method('getRemoteAddress')->willReturn(null);
         $parser->handle($connection);
@@ -773,7 +777,7 @@ public function testServerParamsWontBeSetOnMissingUrls()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
         $clock->expects($this->once())->method('now')->willReturn(1652972091.3958);
 
         $parser = new RequestHeaderParser($clock);
@@ -782,7 +786,7 @@ public function testServerParamsWontBeSetOnMissingUrls()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET /foo HTTP/1.0\r\nHost: example.com\r\n\r\n"]);
@@ -801,12 +805,12 @@ public function testServerParamsWontBeSetOnMissingUrls()
 
     public function testServerParamsWillBeReusedForMultipleRequestsFromSameConnection()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
         $clock->expects($this->exactly(2))->method('now')->willReturn(1652972091.3958);
 
         $parser = new RequestHeaderParser($clock);
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
         $connection->expects($this->once())->method('getLocalAddress')->willReturn('tcp://127.1.1.1:8000');
         $connection->expects($this->once())->method('getRemoteAddress')->willReturn('tcp://192.168.1.1:8001');
 
@@ -837,11 +841,11 @@ public function testServerParamsWillBeReusedForMultipleRequestsFromSameConnectio
 
     public function testServerParamsWillBeRememberedUntilConnectionIsClosed()
     {
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(['getLocalAddress', 'getRemoteAddress'])->getMock();
 
         $parser->handle($connection);
         $connection->emit('data', ["GET /foo HTTP/1.0\r\nHost: example.com\r\n\r\n"]);
@@ -859,7 +863,7 @@ public function testQueryParmetersWillBeSet()
     {
         $request = null;
 
-        $clock = $this->getMockBuilder('React\Http\Io\Clock')->disableOriginalConstructor()->getMock();
+        $clock = $this->createMock(Clock::class);
 
         $parser = new RequestHeaderParser($clock);
 
@@ -867,7 +871,7 @@ public function testQueryParmetersWillBeSet()
             $request = $parsedRequest;
         });
 
-        $connection = $this->getMockBuilder('React\Socket\Connection')->disableOriginalConstructor()->setMethods(null)->getMock();
+        $connection = $this->getMockBuilder(Connection::class)->disableOriginalConstructor()->setMethods(null)->getMock();
         $parser->handle($connection);
 
         $connection->emit('data', ["GET /foo.php?hello=world&test=this HTTP/1.0\r\nHost: example.com\r\n\r\n"]);
diff --git a/tests/Io/SenderTest.php b/tests/Io/SenderTest.php
index 59bb9719..df4c5359 100644
--- a/tests/Io/SenderTest.php
+++ b/tests/Io/SenderTest.php
@@ -3,13 +3,17 @@
 namespace React\Tests\Http\Io;
 
 use Psr\Http\Message\RequestInterface;
+use React\EventLoop\LoopInterface;
 use React\Http\Client\Client as HttpClient;
 use React\Http\Io\ClientConnectionManager;
+use React\Http\Io\ClientRequestStream;
 use React\Http\Io\EmptyBodyStream;
 use React\Http\Io\ReadableBodyStream;
 use React\Http\Io\Sender;
 use React\Http\Message\Request;
 use React\Promise\Promise;
+use React\Socket\ConnectionInterface;
+use React\Socket\ConnectorInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 use function React\Promise\reject;
@@ -25,19 +29,19 @@ class SenderTest extends TestCase
      */
     public function setUpLoop()
     {
-        $this->loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $this->loop = $this->createMock(LoopInterface::class);
     }
 
     public function testCreateFromLoop()
     {
         $sender = Sender::createFromLoop($this->loop, null);
 
-        $this->assertInstanceOf('React\Http\Io\Sender', $sender);
+        $this->assertInstanceOf(Sender::class, $sender);
     }
 
     public function testSenderRejectsInvalidUri()
     {
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->never())->method('connect');
 
         $sender = new Sender(new HttpClient(new ClientConnectionManager($connector, $this->loop)));
@@ -51,12 +55,12 @@ public function testSenderRejectsInvalidUri()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('InvalidArgumentException', $exception);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $exception);
     }
 
     public function testSenderConnectorRejection()
     {
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->willReturn(reject(new \RuntimeException('Rejected')));
 
         $sender = new Sender(new HttpClient(new ClientConnectionManager($connector, $this->loop)));
@@ -70,15 +74,15 @@ public function testSenderConnectorRejection()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
     }
 
     public function testSendPostWillAutomaticallySendContentLengthHeader()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Content-Length') === '5';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -88,10 +92,10 @@ public function testSendPostWillAutomaticallySendContentLengthHeader()
 
     public function testSendPostWillAutomaticallySendContentLengthZeroHeaderForEmptyRequestBody()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Content-Length') === '0';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -101,10 +105,10 @@ public function testSendPostWillAutomaticallySendContentLengthZeroHeaderForEmpty
 
     public function testSendPostStreamWillAutomaticallySendTransferEncodingChunked()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('write')->with("");
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Transfer-Encoding') === 'chunked';
         }))->willReturn($outgoing);
@@ -118,11 +122,11 @@ public function testSendPostStreamWillAutomaticallySendTransferEncodingChunked()
 
     public function testSendPostStreamWillAutomaticallyPipeChunkEncodeBodyForWriteAndRespectRequestThrottling()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('isWritable')->willReturn(true);
         $outgoing->expects($this->exactly(2))->method('write')->withConsecutive([""], ["5\r\nhello\r\n"])->willReturn(false);
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->willReturn($outgoing);
 
         $sender = new Sender($client);
@@ -137,12 +141,12 @@ public function testSendPostStreamWillAutomaticallyPipeChunkEncodeBodyForWriteAn
 
     public function testSendPostStreamWillAutomaticallyPipeChunkEncodeBodyForEnd()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('isWritable')->willReturn(true);
         $outgoing->expects($this->exactly(2))->method('write')->withConsecutive([""], ["0\r\n\r\n"])->willReturn(false);
         $outgoing->expects($this->once())->method('end')->with(null);
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->willReturn($outgoing);
 
         $sender = new Sender($client);
@@ -156,13 +160,13 @@ public function testSendPostStreamWillAutomaticallyPipeChunkEncodeBodyForEnd()
 
     public function testSendPostStreamWillRejectWhenRequestBodyEmitsErrorEvent()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('isWritable')->willReturn(true);
         $outgoing->expects($this->once())->method('write')->with("")->willReturn(false);
         $outgoing->expects($this->never())->method('end');
         $outgoing->expects($this->once())->method('close');
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->willReturn($outgoing);
 
         $sender = new Sender($client);
@@ -179,20 +183,20 @@ public function testSendPostStreamWillRejectWhenRequestBodyEmitsErrorEvent()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Request failed because request body reported an error', $exception->getMessage());
         $this->assertSame($expected, $exception->getPrevious());
     }
 
     public function testSendPostStreamWillRejectWhenRequestBodyClosesWithoutEnd()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('isWritable')->willReturn(true);
         $outgoing->expects($this->once())->method('write')->with("")->willReturn(false);
         $outgoing->expects($this->never())->method('end');
         $outgoing->expects($this->once())->method('close');
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->willReturn($outgoing);
 
         $sender = new Sender($client);
@@ -208,19 +212,19 @@ public function testSendPostStreamWillRejectWhenRequestBodyClosesWithoutEnd()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Request failed because request body closed unexpectedly', $exception->getMessage());
     }
 
     public function testSendPostStreamWillNotRejectWhenRequestBodyClosesAfterEnd()
     {
-        $outgoing = $this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock();
+        $outgoing = $this->createMock(ClientRequestStream::class);
         $outgoing->expects($this->once())->method('isWritable')->willReturn(true);
         $outgoing->expects($this->exactly(2))->method('write')->withConsecutive([""], ["0\r\n\r\n"])->willReturn(false);
         $outgoing->expects($this->once())->method('end');
         $outgoing->expects($this->never())->method('close');
 
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->willReturn($outgoing);
 
         $sender = new Sender($client);
@@ -242,10 +246,10 @@ public function testSendPostStreamWillNotRejectWhenRequestBodyClosesAfterEnd()
 
     public function testSendPostStreamWithExplicitContentLengthWillSendHeaderAsIs()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Content-Length') === '100';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -256,10 +260,10 @@ public function testSendPostStreamWithExplicitContentLengthWillSendHeaderAsIs()
 
     public function testSendGetWillNotPassContentLengthHeaderForEmptyRequestBody()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return !$request->hasHeader('Content-Length');
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -269,10 +273,10 @@ public function testSendGetWillNotPassContentLengthHeaderForEmptyRequestBody()
 
     public function testSendGetWithEmptyBodyStreamWillNotPassContentLengthOrTransferEncodingHeader()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return !$request->hasHeader('Content-Length') && !$request->hasHeader('Transfer-Encoding');
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -284,10 +288,10 @@ public function testSendGetWithEmptyBodyStreamWillNotPassContentLengthOrTransfer
 
     public function testSendCustomMethodWillNotPassContentLengthHeaderForEmptyRequestBody()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return !$request->hasHeader('Content-Length');
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -297,10 +301,10 @@ public function testSendCustomMethodWillNotPassContentLengthHeaderForEmptyReques
 
     public function testSendCustomMethodWithExplicitContentLengthZeroWillBePassedAsIs()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Content-Length') === '0';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -311,10 +315,10 @@ public function testSendCustomMethodWithExplicitContentLengthZeroWillBePassedAsI
     /** @test */
     public function getRequestWithUserAndPassShouldSendAGetRequestWithBasicAuthorizationHeader()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Authorization') === 'Basic am9objpkdW1teQ==';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -325,10 +329,10 @@ public function getRequestWithUserAndPassShouldSendAGetRequestWithBasicAuthoriza
     /** @test */
     public function getRequestWithUserAndPassShouldSendAGetRequestWithGivenAuthorizationHeaderBasicAuthorizationHeader()
     {
-        $client = $this->getMockBuilder('React\Http\Client\Client')->disableOriginalConstructor()->getMock();
+        $client = $this->createMock(HttpClient::class);
         $client->expects($this->once())->method('request')->with($this->callback(function (RequestInterface $request) {
             return $request->getHeaderLine('Authorization') === 'bearer abc123';
-        }))->willReturn($this->getMockBuilder('React\Http\Io\ClientRequestStream')->disableOriginalConstructor()->getMock());
+        }))->willReturn($this->createMock(ClientRequestStream::class));
 
         $sender = new Sender($client);
 
@@ -342,7 +346,7 @@ public function testCancelRequestWillCancelConnector()
             throw new \RuntimeException();
         });
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->willReturn($promise);
 
         $sender = new Sender(new HttpClient(new ClientConnectionManager($connector, $this->loop)));
@@ -357,15 +361,15 @@ public function testCancelRequestWillCancelConnector()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
     }
 
     public function testCancelRequestWillCloseConnection()
     {
-        $connection = $this->getMockBuilder('React\Socket\ConnectionInterface')->getMock();
+        $connection = $this->createMock(ConnectionInterface::class);
         $connection->expects($this->once())->method('close');
 
-        $connector = $this->getMockBuilder('React\Socket\ConnectorInterface')->getMock();
+        $connector = $this->createMock(ConnectorInterface::class);
         $connector->expects($this->once())->method('connect')->willReturn(resolve($connection));
 
         $sender = new Sender(new HttpClient(new ClientConnectionManager($connector, $this->loop)));
@@ -380,6 +384,6 @@ public function testCancelRequestWillCloseConnection()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
     }
 }
diff --git a/tests/Io/StreamingServerTest.php b/tests/Io/StreamingServerTest.php
index 3b5f28f4..a61d1425 100644
--- a/tests/Io/StreamingServerTest.php
+++ b/tests/Io/StreamingServerTest.php
@@ -4,11 +4,14 @@
 
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Message\StreamInterface;
 use React\EventLoop\Loop;
+use React\Http\Io\RequestHeaderParser;
 use React\Http\Io\StreamingServer;
 use React\Http\Message\Response;
 use React\Http\Message\ServerRequest;
 use React\Promise\Promise;
+use React\Socket\Connection;
 use React\Stream\ThroughStream;
 use React\Tests\Http\SocketServerStub;
 use React\Tests\Http\TestCase;
@@ -35,7 +38,7 @@ public function setUpConnectionMockAndSocket()
 
     private function mockConnection(array $additionalMethods = null)
     {
-        $connection = $this->getMockBuilder('React\Socket\Connection')
+        $connection = $this->getMockBuilder(Connection::class)
             ->disableOriginalConstructor()
             ->setMethods(array_merge(
                 [
@@ -125,7 +128,7 @@ public function testRequestEvent()
         $serverParams = $requestAssertion->getServerParams();
 
         $this->assertSame(1, $i);
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -158,7 +161,7 @@ public function testRequestEventWithSingleRequestHandlerArray()
         $serverParams = $requestAssertion->getServerParams();
 
         $this->assertSame(1, $i);
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -181,7 +184,7 @@ public function testRequestGetWithHostAndCustomPort()
         $data = "GET / HTTP/1.1\r\nHost: example.com:8080\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -203,7 +206,7 @@ public function testRequestGetWithHostAndHttpsPort()
         $data = "GET / HTTP/1.1\r\nHost: example.com:443\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -225,7 +228,7 @@ public function testRequestGetWithHostAndDefaultPortWillBeIgnored()
         $data = "GET / HTTP/1.1\r\nHost: example.com\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -247,7 +250,7 @@ public function testRequestGetHttp10WithoutHostWillBeIgnored()
         $data = "GET / HTTP/1.0\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/', $requestAssertion->getRequestTarget());
         $this->assertSame('/', $requestAssertion->getUri()->getPath());
@@ -282,7 +285,7 @@ public function testRequestOptionsAsterisk()
         $data = "OPTIONS * HTTP/1.1\r\nHost: example.com\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('OPTIONS', $requestAssertion->getMethod());
         $this->assertSame('*', $requestAssertion->getRequestTarget());
         $this->assertSame('', $requestAssertion->getUri()->getPath());
@@ -315,7 +318,7 @@ public function testRequestConnectAuthorityForm()
         $data = "CONNECT example.com:443 HTTP/1.1\r\nHost: example.com:443\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('CONNECT', $requestAssertion->getMethod());
         $this->assertSame('example.com:443', $requestAssertion->getRequestTarget());
         $this->assertSame('', $requestAssertion->getUri()->getPath());
@@ -337,7 +340,7 @@ public function testRequestConnectWithoutHostWillBePassesAsIs()
         $data = "CONNECT example.com:443 HTTP/1.1\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('CONNECT', $requestAssertion->getMethod());
         $this->assertSame('example.com:443', $requestAssertion->getRequestTarget());
         $this->assertSame('', $requestAssertion->getUri()->getPath());
@@ -359,7 +362,7 @@ public function testRequestConnectAuthorityFormWithDefaultPortWillBePassedAsIs()
         $data = "CONNECT example.com:80 HTTP/1.1\r\nHost: example.com:80\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('CONNECT', $requestAssertion->getMethod());
         $this->assertSame('example.com:80', $requestAssertion->getRequestTarget());
         $this->assertSame('', $requestAssertion->getUri()->getPath());
@@ -381,7 +384,7 @@ public function testRequestConnectAuthorityFormNonMatchingHostWillBePassedAsIs()
         $data = "CONNECT example.com:80 HTTP/1.1\r\nHost: other.example.org\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('CONNECT', $requestAssertion->getMethod());
         $this->assertSame('example.com:80', $requestAssertion->getRequestTarget());
         $this->assertSame('', $requestAssertion->getUri()->getPath());
@@ -433,7 +436,7 @@ public function testRequestWithoutHostEventUsesSocketAddress()
         $data = "GET /test HTTP/1.0\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('/test', $requestAssertion->getRequestTarget());
         $this->assertEquals('http://127.0.0.1/test', $requestAssertion->getUri());
@@ -454,7 +457,7 @@ public function testRequestAbsoluteEvent()
         $data = "GET http://example.com/test HTTP/1.1\r\nHost: example.com\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('http://example.com/test', $requestAssertion->getRequestTarget());
         $this->assertEquals('http://example.com/test', $requestAssertion->getUri());
@@ -476,7 +479,7 @@ public function testRequestAbsoluteNonMatchingHostWillBePassedAsIs()
         $data = "GET http://example.com/test HTTP/1.1\r\nHost: other.example.org\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('GET', $requestAssertion->getMethod());
         $this->assertSame('http://example.com/test', $requestAssertion->getRequestTarget());
         $this->assertEquals('http://example.com/test', $requestAssertion->getUri());
@@ -510,7 +513,7 @@ public function testRequestOptionsAsteriskEvent()
         $data = "OPTIONS * HTTP/1.1\r\nHost: example.com\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('OPTIONS', $requestAssertion->getMethod());
         $this->assertSame('*', $requestAssertion->getRequestTarget());
         $this->assertEquals('http://example.com', $requestAssertion->getUri());
@@ -532,7 +535,7 @@ public function testRequestOptionsAbsoluteEvent()
         $data = "OPTIONS http://example.com HTTP/1.1\r\nHost: example.com\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $requestAssertion);
+        $this->assertInstanceOf(ServerRequestInterface::class, $requestAssertion);
         $this->assertSame('OPTIONS', $requestAssertion->getMethod());
         $this->assertSame('http://example.com', $requestAssertion->getRequestTarget());
         $this->assertEquals('http://example.com', $requestAssertion->getUri());
@@ -698,12 +701,10 @@ public function testResponseContainsServerHeader()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -712,7 +713,7 @@ function ($data) use (&$buffer) {
         $data = $this->createGetRequest();
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("\r\nServer: ReactPHP/1\r\n", $buffer);
+        $this->assertStringContainsString("\r\nServer: ReactPHP/1\r\n", $buffer);
     }
 
     public function testResponsePendingPromiseWillNotSendAnything()
@@ -728,12 +729,10 @@ public function testResponsePendingPromiseWillNotSendAnything()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -758,12 +757,10 @@ public function testResponsePendingPromiseWillBeCancelledIfConnectionCloses()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -794,12 +791,10 @@ public function testResponseBodyStreamAlreadyClosedWillSendEmptyBodyChunkedEncod
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -829,12 +824,10 @@ public function testResponseBodyStreamEndingWillSendEmptyBodyChunkedEncoded()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -867,12 +860,10 @@ public function testResponseBodyStreamAlreadyClosedWillSendEmptyBodyPlainHttp10(
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -903,15 +894,13 @@ public function testResponseStreamWillBeClosedIfConnectionIsAlreadyClosed()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
-        $this->connection = $this->getMockBuilder('React\Socket\Connection')
+        $this->connection = $this->getMockBuilder(Connection::class)
             ->disableOriginalConstructor()
             ->setMethods(
                 [
@@ -980,12 +969,10 @@ public function testResponseUpgradeInResponseCanBeUsedToAdvertisePossibleUpgrade
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1015,12 +1002,10 @@ public function testResponseUpgradeWishInRequestCanBeIgnoredByReturningNormalRes
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1053,12 +1038,10 @@ public function testResponseUpgradeSwitchingProtocolIncludesConnectionUpgradeHea
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1091,12 +1074,10 @@ public function testResponseUpgradeSwitchingProtocolWithStreamWillPipeDataToConn
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1128,12 +1109,10 @@ public function testResponseConnectMethodStreamWillPipeDataToConnection()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1185,12 +1164,10 @@ public function testResponseContainsSameRequestProtocolVersionAndChunkedBodyForH
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1199,8 +1176,8 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("bye", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("bye", $buffer);
     }
 
     public function testResponseContainsSameRequestProtocolVersionAndRawBodyForHttp10()
@@ -1218,12 +1195,10 @@ public function testResponseContainsSameRequestProtocolVersionAndRawBodyForHttp1
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1232,9 +1207,9 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.0\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.0 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
-        $this->assertContainsString("bye", $buffer);
+        $this->assertStringContainsString("HTTP/1.0 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("bye", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyForHeadRequest()
@@ -1251,12 +1226,10 @@ public function testResponseContainsNoResponseBodyForHeadRequest()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1265,9 +1238,9 @@ function ($data) use (&$buffer) {
         $data = "HEAD / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
-        $this->assertNotContainsString("bye", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringNotContainsString("bye", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyForHeadRequestWithStreamingResponse()
@@ -1287,12 +1260,10 @@ public function testResponseContainsNoResponseBodyForHeadRequestWithStreamingRes
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1301,8 +1272,8 @@ function ($data) use (&$buffer) {
         $data = "HEAD / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyAndNoContentLengthForNoContentStatus()
@@ -1319,12 +1290,10 @@ public function testResponseContainsNoResponseBodyAndNoContentLengthForNoContent
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1333,9 +1302,9 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 204 No Content\r\n", $buffer);
-        $this->assertNotContainsString("\r\nContent-Length: 3\r\n", $buffer);
-        $this->assertNotContainsString("bye", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 204 No Content\r\n", $buffer);
+        $this->assertStringNotContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringNotContainsString("bye", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyAndNoContentLengthForNoContentStatusResponseWithStreamingBody()
@@ -1355,12 +1324,10 @@ public function testResponseContainsNoResponseBodyAndNoContentLengthForNoContent
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1369,8 +1336,8 @@ function ($data) use (&$buffer) {
         $data = "HEAD / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 204 No Content\r\n", $buffer);
-        $this->assertNotContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 204 No Content\r\n", $buffer);
+        $this->assertStringNotContainsString("\r\nContent-Length: 3\r\n", $buffer);
     }
 
     public function testResponseContainsNoContentLengthHeaderForNotModifiedStatus()
@@ -1387,12 +1354,10 @@ public function testResponseContainsNoContentLengthHeaderForNotModifiedStatus()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1401,8 +1366,8 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
-        $this->assertNotContainsString("\r\nContent-Length: 0\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
+        $this->assertStringNotContainsString("\r\nContent-Length: 0\r\n", $buffer);
     }
 
     public function testResponseContainsExplicitContentLengthHeaderForNotModifiedStatus()
@@ -1419,12 +1384,10 @@ public function testResponseContainsExplicitContentLengthHeaderForNotModifiedSta
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1433,8 +1396,8 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
     }
 
     public function testResponseContainsExplicitContentLengthHeaderForHeadRequests()
@@ -1451,12 +1414,10 @@ public function testResponseContainsExplicitContentLengthHeaderForHeadRequests()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1465,8 +1426,8 @@ function ($data) use (&$buffer) {
         $data = "HEAD / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyForNotModifiedStatus()
@@ -1483,12 +1444,10 @@ public function testResponseContainsNoResponseBodyForNotModifiedStatus()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1497,9 +1456,9 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
-        $this->assertNotContainsString("bye", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringNotContainsString("bye", $buffer);
     }
 
     public function testResponseContainsNoResponseBodyForNotModifiedStatusWithStreamingBody()
@@ -1519,12 +1478,10 @@ public function testResponseContainsNoResponseBodyForNotModifiedStatusWithStream
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1533,8 +1490,8 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
-        $this->assertContainsString("\r\nContent-Length: 3\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 304 Not Modified\r\n", $buffer);
+        $this->assertStringContainsString("\r\nContent-Length: 3\r\n", $buffer);
     }
 
     public function testRequestInvalidHttpProtocolVersionWillEmitErrorAndSendErrorResponse()
@@ -1550,12 +1507,10 @@ public function testRequestInvalidHttpProtocolVersionWillEmitErrorAndSendErrorRe
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1564,11 +1519,11 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.2\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
 
-        $this->assertContainsString("HTTP/1.1 505 HTTP Version Not Supported\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
-        $this->assertContainsString("Error 505: HTTP Version Not Supported", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 505 HTTP Version Not Supported\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("Error 505: HTTP Version Not Supported", $buffer);
     }
 
     public function testRequestOverflowWillEmitErrorAndSendErrorResponse()
@@ -1584,12 +1539,10 @@ public function testRequestOverflowWillEmitErrorAndSendErrorResponse()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1599,10 +1552,10 @@ function ($data) use (&$buffer) {
         $data .= str_repeat('A', 8193 - strlen($data)) . "\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('OverflowException', $error);
+        $this->assertInstanceOf(\OverflowException::class, $error);
 
-        $this->assertContainsString("HTTP/1.1 431 Request Header Fields Too Large\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\nError 431: Request Header Fields Too Large", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 431 Request Header Fields Too Large\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\nError 431: Request Header Fields Too Large", $buffer);
     }
 
     public function testRequestInvalidWillEmitErrorAndSendErrorResponse()
@@ -1618,12 +1571,10 @@ public function testRequestInvalidWillEmitErrorAndSendErrorResponse()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -1632,10 +1583,10 @@ function ($data) use (&$buffer) {
         $data = "bad request\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('InvalidArgumentException', $error);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $error);
 
-        $this->assertContainsString("HTTP/1.1 400 Bad Request\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\nError 400: Bad Request", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 400 Bad Request\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\nError 400: Bad Request", $buffer);
     }
 
     public function testRequestContentLengthBodyDataWillEmitDataEventOnRequestStream()
@@ -1959,7 +1910,7 @@ public function testRequestZeroContentLengthWillEmitEndAndAdditionalDataWillBeIg
 
     public function testRequestInvalidChunkHeaderTooLongWillEmitErrorOnRequestStream()
     {
-        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf('Exception'));
+        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class));
         $server = new StreamingServer(Loop::get(), function ($request) use ($errorEvent){
             $request->getBody()->on('error', $errorEvent);
             return resolve(new Response());
@@ -1984,7 +1935,7 @@ public function testRequestInvalidChunkHeaderTooLongWillEmitErrorOnRequestStream
 
     public function testRequestInvalidChunkBodyTooLongWillEmitErrorOnRequestStream()
     {
-        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf('Exception'));
+        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class));
         $server = new StreamingServer(Loop::get(), function ($request) use ($errorEvent){
             $request->getBody()->on('error', $errorEvent);
         });
@@ -2006,7 +1957,7 @@ public function testRequestInvalidChunkBodyTooLongWillEmitErrorOnRequestStream()
 
     public function testRequestUnexpectedEndOfRequestWithChunkedTransferConnectionWillEmitErrorOnRequestStream()
     {
-        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf('Exception'));
+        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class));
         $server = new StreamingServer(Loop::get(), function ($request) use ($errorEvent){
             $request->getBody()->on('error', $errorEvent);
         });
@@ -2029,7 +1980,7 @@ public function testRequestUnexpectedEndOfRequestWithChunkedTransferConnectionWi
 
     public function testRequestInvalidChunkHeaderWillEmitErrorOnRequestStream()
     {
-        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf('Exception'));
+        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class));
         $server = new StreamingServer(Loop::get(), function ($request) use ($errorEvent){
             $request->getBody()->on('error', $errorEvent);
         });
@@ -2051,7 +2002,7 @@ public function testRequestInvalidChunkHeaderWillEmitErrorOnRequestStream()
 
     public function testRequestUnexpectedEndOfRequestWithContentLengthWillEmitErrorOnRequestStream()
     {
-        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf('Exception'));
+        $errorEvent = $this->expectCallableOnceWith($this->isInstanceOf(\Exception::class));
         $server = new StreamingServer(Loop::get(), function ($request) use ($errorEvent){
             $request->getBody()->on('error', $errorEvent);
         });
@@ -2134,12 +2085,10 @@ public function testResponseWithBodyStreamWillUseChunkedTransferEncodingByDefaul
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2150,8 +2099,8 @@ function ($data) use (&$buffer) {
         $this->connection->emit('data', [$data]);
         $stream->emit('data', ['hello']);
 
-        $this->assertContainsString("Transfer-Encoding: chunked", $buffer);
-        $this->assertContainsString("hello", $buffer);
+        $this->assertStringContainsString("Transfer-Encoding: chunked", $buffer);
+        $this->assertStringContainsString("hello", $buffer);
     }
 
     public function testResponseWithBodyStringWillOverwriteExplicitContentLengthAndTransferEncoding()
@@ -2171,12 +2120,10 @@ public function testResponseWithBodyStringWillOverwriteExplicitContentLengthAndT
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2186,14 +2133,14 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertNotContainsString("Transfer-Encoding: chunked", $buffer);
-        $this->assertContainsString("Content-Length: 5", $buffer);
-        $this->assertContainsString("hello", $buffer);
+        $this->assertStringNotContainsString("Transfer-Encoding: chunked", $buffer);
+        $this->assertStringContainsString("Content-Length: 5", $buffer);
+        $this->assertStringContainsString("hello", $buffer);
     }
 
     public function testResponseContainsResponseBodyWithTransferEncodingChunkedForBodyWithUnknownSize()
     {
-        $body = $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock();
+        $body = $this->createMock(StreamInterface::class);
         $body->expects($this->once())->method('getSize')->willReturn(null);
         $body->expects($this->once())->method('__toString')->willReturn('body');
 
@@ -2209,12 +2156,10 @@ public function testResponseContainsResponseBodyWithTransferEncodingChunkedForBo
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2223,14 +2168,14 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("Transfer-Encoding: chunked", $buffer);
-        $this->assertNotContainsString("Content-Length:", $buffer);
-        $this->assertContainsString("body", $buffer);
+        $this->assertStringContainsString("Transfer-Encoding: chunked", $buffer);
+        $this->assertStringNotContainsString("Content-Length:", $buffer);
+        $this->assertStringContainsString("body", $buffer);
     }
 
     public function testResponseContainsResponseBodyWithPlainBodyWithUnknownSizeForLegacyHttp10()
     {
-        $body = $this->getMockBuilder('Psr\Http\Message\StreamInterface')->getMock();
+        $body = $this->createMock(StreamInterface::class);
         $body->expects($this->once())->method('getSize')->willReturn(null);
         $body->expects($this->once())->method('__toString')->willReturn('body');
 
@@ -2246,12 +2191,10 @@ public function testResponseContainsResponseBodyWithPlainBodyWithUnknownSizeForL
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2260,9 +2203,9 @@ function ($data) use (&$buffer) {
         $data = "GET / HTTP/1.0\r\nHost: localhost\r\n\r\n";
         $this->connection->emit('data', [$data]);
 
-        $this->assertNotContainsString("Transfer-Encoding: chunked", $buffer);
-        $this->assertNotContainsString("Content-Length:", $buffer);
-        $this->assertContainsString("body", $buffer);
+        $this->assertStringNotContainsString("Transfer-Encoding: chunked", $buffer);
+        $this->assertStringNotContainsString("Content-Length:", $buffer);
+        $this->assertStringContainsString("body", $buffer);
     }
 
     public function testResponseWithCustomTransferEncodingWillBeIgnoredAndUseChunkedTransferEncodingInstead()
@@ -2282,12 +2225,10 @@ public function testResponseWithCustomTransferEncodingWillBeIgnoredAndUseChunked
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2298,9 +2239,9 @@ function ($data) use (&$buffer) {
         $this->connection->emit('data', [$data]);
         $stream->emit('data', ['hello']);
 
-        $this->assertContainsString('Transfer-Encoding: chunked', $buffer);
-        $this->assertNotContainsString('Transfer-Encoding: custom', $buffer);
-        $this->assertContainsString("5\r\nhello\r\n", $buffer);
+        $this->assertStringContainsString('Transfer-Encoding: chunked', $buffer);
+        $this->assertStringNotContainsString('Transfer-Encoding: custom', $buffer);
+        $this->assertStringContainsString("5\r\nhello\r\n", $buffer);
     }
 
     public function testResponseWithoutExplicitDateHeaderWillAddCurrentDateFromClock()
@@ -2321,12 +2262,10 @@ public function testResponseWithoutExplicitDateHeaderWillAddCurrentDateFromClock
             $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2336,9 +2275,9 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("Date: Thu, 19 May 2022 14:54:51 GMT\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("Date: Thu, 19 May 2022 14:54:51 GMT\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
     }
 
     public function testResponseWithCustomDateHeaderOverwritesDefault()
@@ -2354,12 +2293,10 @@ public function testResponseWithCustomDateHeaderOverwritesDefault()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2369,9 +2306,9 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("Date: Tue, 15 Nov 1994 08:12:31 GMT\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("Date: Tue, 15 Nov 1994 08:12:31 GMT\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
     }
 
     public function testResponseWithEmptyDateHeaderRemovesDateHeader()
@@ -2387,12 +2324,10 @@ public function testResponseWithEmptyDateHeaderRemovesDateHeader()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2402,9 +2337,9 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertNotContainsString("Date:", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringNotContainsString("Date:", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
     }
 
     public function testResponseCanContainMultipleCookieHeaders()
@@ -2427,12 +2362,10 @@ public function testResponseCanContainMultipleCookieHeaders()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2455,12 +2388,10 @@ public function testReponseWithExpectContinueRequestContainsContinueWithLaterRes
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2473,8 +2404,8 @@ function ($data) use (&$buffer) {
         $data .= "\r\n";
 
         $this->connection->emit('data', [$data]);
-        $this->assertContainsString("HTTP/1.1 100 Continue\r\n", $buffer);
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 100 Continue\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
     }
 
     public function testResponseWithExpectContinueRequestWontSendContinueForHttp10()
@@ -2487,12 +2418,10 @@ public function testResponseWithExpectContinueRequestWontSendContinueForHttp10()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2503,13 +2432,13 @@ function ($data) use (&$buffer) {
         $data .= "\r\n";
 
         $this->connection->emit('data', [$data]);
-        $this->assertContainsString("HTTP/1.0 200 OK\r\n", $buffer);
-        $this->assertNotContainsString("HTTP/1.1 100 Continue\r\n\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.0 200 OK\r\n", $buffer);
+        $this->assertStringNotContainsString("HTTP/1.1 100 Continue\r\n\r\n", $buffer);
     }
 
     public function testInvalidCallbackFunctionLeadsToException()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new StreamingServer(Loop::get(), 'invalid');
     }
 
@@ -2529,12 +2458,10 @@ public function testResponseBodyStreamWillStreamDataWithChunkedTransferEncoding(
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2546,10 +2473,10 @@ function ($data) use (&$buffer) {
         $input->emit('data', ['1']);
         $input->emit('data', ['23']);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
-        $this->assertContainsString("1\r\n1\r\n", $buffer);
-        $this->assertContainsString("2\r\n23\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("1\r\n1\r\n", $buffer);
+        $this->assertStringContainsString("2\r\n23\r\n", $buffer);
     }
 
     public function testResponseBodyStreamWithContentLengthWillStreamTillLengthWithoutTransferEncoding()
@@ -2568,12 +2495,10 @@ public function testResponseBodyStreamWithContentLengthWillStreamTillLengthWitho
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2585,11 +2510,11 @@ function ($data) use (&$buffer) {
         $input->emit('data', ['hel']);
         $input->emit('data', ['lo']);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("Content-Length: 5\r\n", $buffer);
-        $this->assertNotContainsString("Transfer-Encoding", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
-        $this->assertContainsString("hello", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("Content-Length: 5\r\n", $buffer);
+        $this->assertStringNotContainsString("Transfer-Encoding", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("hello", $buffer);
     }
 
     public function testResponseWithResponsePromise()
@@ -2602,12 +2527,10 @@ public function testResponseWithResponsePromise()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2616,8 +2539,8 @@ function ($data) use (&$buffer) {
         $data = $this->createGetRequest();
 
         $this->connection->emit('data', [$data]);
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("\r\n\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("\r\n\r\n", $buffer);
     }
 
     public function testResponseReturnInvalidTypeWillResultInError()
@@ -2635,12 +2558,10 @@ public function testResponseReturnInvalidTypeWillResultInError()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2650,8 +2571,8 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
     }
 
     public function testResponseResolveWrongTypeInPromiseWillResultInError()
@@ -2664,12 +2585,10 @@ public function testResponseResolveWrongTypeInPromiseWillResultInError()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2679,7 +2598,7 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
     }
 
     public function testResponseRejectedPromiseWillResultInErrorMessage()
@@ -2695,12 +2614,10 @@ public function testResponseRejectedPromiseWillResultInErrorMessage()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2710,7 +2627,7 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
     }
 
     public function testResponseExceptionInCallbackWillResultInErrorMessage()
@@ -2726,12 +2643,10 @@ public function testResponseExceptionInCallbackWillResultInErrorMessage()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2741,7 +2656,7 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
     }
 
     public function testResponseWithContentLengthHeaderForStringBodyOverwritesTransferEncoding()
@@ -2758,12 +2673,10 @@ public function testResponseWithContentLengthHeaderForStringBodyOverwritesTransf
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2773,11 +2686,11 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
-        $this->assertContainsString("Content-Length: 5\r\n", $buffer);
-        $this->assertContainsString("hello", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("Content-Length: 5\r\n", $buffer);
+        $this->assertStringContainsString("hello", $buffer);
 
-        $this->assertNotContainsString("Transfer-Encoding", $buffer);
+        $this->assertStringNotContainsString("Transfer-Encoding", $buffer);
     }
 
     public function testResponseWillBeHandled()
@@ -2790,12 +2703,10 @@ public function testResponseWillBeHandled()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2805,7 +2716,7 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 200 OK\r\n", $buffer);
+        $this->assertStringContainsString("HTTP/1.1 200 OK\r\n", $buffer);
     }
 
     public function testResponseExceptionThrowInCallBackFunctionWillResultInErrorMessage()
@@ -2823,12 +2734,10 @@ public function testResponseExceptionThrowInCallBackFunctionWillResultInErrorMes
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2838,8 +2747,8 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertInstanceOf('RuntimeException', $exception);
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
         $this->assertEquals('hello', $exception->getPrevious()->getMessage());
     }
 
@@ -2858,12 +2767,10 @@ public function testResponseThrowableThrowInCallBackFunctionWillResultInErrorMes
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2881,8 +2788,8 @@ function ($data) use (&$buffer) {
             );
         }
 
-        $this->assertInstanceOf('RuntimeException', $exception);
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
         $this->assertEquals('hello', $exception->getPrevious()->getMessage());
     }
 
@@ -2903,12 +2810,10 @@ public function testResponseRejectOfNonExceptionWillResultInErrorMessage()
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -2918,54 +2823,52 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
     }
 
     public static function provideInvalidResponse()
     {
         $response = new Response(200, [], '', '1.1', 'OK');
 
-        return [
-            [
-                $response->withStatus(99, 'OK')
-            ],
-            [
-                $response->withStatus(1000, 'OK')
-            ],
-            [
-                $response->withStatus(200, "Invald\r\nReason: Yes")
-            ],
-            [
-                $response->withHeader('Invalid', "Yes\r\n")
-            ],
-            [
-                $response->withHeader('Invalid', "Yes\n")
-            ],
-            [
-                $response->withHeader('Invalid', "Yes\r")
-            ],
-            [
-                $response->withHeader("Inva\r\nlid", 'Yes')
-            ],
-            [
-                $response->withHeader("Inva\nlid", 'Yes')
-            ],
-            [
-                $response->withHeader("Inva\rlid", 'Yes')
-            ],
-            [
-                $response->withHeader('Inva Lid', 'Yes')
-            ],
-            [
-                $response->withHeader('Inva:Lid', 'Yes')
-            ],
-            [
-                $response->withHeader('Invalid', "Val\0ue")
-            ],
-            [
-                $response->withHeader("Inva\0lid", 'Yes')
-            ]
+        yield [
+            $response->withStatus(99, 'OK')
+        ];
+        yield [
+            $response->withStatus(1000, 'OK')
+        ];
+        yield [
+            $response->withStatus(200, "Invald\r\nReason: Yes")
+        ];
+        yield [
+            $response->withHeader('Invalid', "Yes\r\n")
+        ];
+        yield [
+            $response->withHeader('Invalid', "Yes\n")
+        ];
+        yield [
+            $response->withHeader('Invalid', "Yes\r")
+        ];
+        yield [
+            $response->withHeader("Inva\r\nlid", 'Yes')
+        ];
+        yield [
+            $response->withHeader("Inva\nlid", 'Yes')
+        ];
+        yield [
+            $response->withHeader("Inva\rlid", 'Yes')
+        ];
+        yield [
+            $response->withHeader('Inva Lid', 'Yes')
+        ];
+        yield [
+            $response->withHeader('Inva:Lid', 'Yes')
+        ];
+        yield [
+            $response->withHeader('Invalid', "Val\0ue")
+        ];
+        yield [
+            $response->withHeader("Inva\0lid", 'Yes')
         ];
     }
 
@@ -2988,12 +2891,10 @@ public function testInvalidResponseObjectWillResultInErrorMessage(ResponseInterf
         $this->connection
             ->expects($this->any())
             ->method('write')
-            ->will(
-                $this->returnCallback(
-                    function ($data) use (&$buffer) {
-                        $buffer .= $data;
-                    }
-                )
+            ->willReturnCallback(
+                function ($data) use (&$buffer) {
+                    $buffer .= $data;
+                }
             );
 
         $server->listen($this->socket);
@@ -3003,8 +2904,8 @@ function ($data) use (&$buffer) {
 
         $this->connection->emit('data', [$data]);
 
-        $this->assertContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
-        $this->assertInstanceOf('InvalidArgumentException', $exception);
+        $this->assertStringContainsString("HTTP/1.1 500 Internal Server Error\r\n", $buffer);
+        $this->assertInstanceOf(\InvalidArgumentException::class, $exception);
     }
 
     public function testRequestServerRequestParams()
@@ -3147,7 +3048,7 @@ public function testNewConnectionWillInvokeParserOnce()
     {
         $server = new StreamingServer(Loop::get(), $this->expectCallableNever());
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->once())->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3164,7 +3065,7 @@ public function testNewConnectionWillInvokeParserOnceAndInvokeRequestHandlerWhen
 
         $server = new StreamingServer(Loop::get(), $this->expectCallableOnceWith($request));
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->once())->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3187,7 +3088,7 @@ public function testNewConnectionWillInvokeParserOnceAndInvokeRequestHandlerWhen
 
         $server = new StreamingServer(Loop::get(), $this->expectCallableOnceWith($request));
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->once())->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3212,7 +3113,7 @@ public function testNewConnectionWillInvokeParserOnceAndInvokeRequestHandlerWhen
             return new Response(200, ['Connection' => 'close']);
         });
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->once())->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3237,7 +3138,7 @@ public function testNewConnectionWillInvokeParserTwiceAfterInvokingRequestHandle
             return new Response();
         });
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->exactly(2))->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3262,7 +3163,7 @@ public function testNewConnectionWillInvokeParserTwiceAfterInvokingRequestHandle
             return new Response();
         });
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->exactly(2))->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3288,7 +3189,7 @@ public function testNewConnectionWillInvokeParserOnceAfterInvokingRequestHandler
             return new Response(200, [], $body);
         });
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->once())->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
@@ -3314,7 +3215,7 @@ public function testNewConnectionWillInvokeParserTwiceAfterInvokingRequestHandle
             return new Response(200, [], $body);
         });
 
-        $parser = $this->getMockBuilder('React\Http\Io\RequestHeaderParser')->disableOriginalConstructor()->getMock();
+        $parser = $this->createMock(RequestHeaderParser::class);
         $parser->expects($this->exactly(2))->method('handle');
 
         $ref = new \ReflectionProperty($server, 'parser');
diff --git a/tests/Io/TransactionTest.php b/tests/Io/TransactionTest.php
index b4825024..3833cfd3 100644
--- a/tests/Io/TransactionTest.php
+++ b/tests/Io/TransactionTest.php
@@ -5,7 +5,10 @@
 use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use React\EventLoop\LoopInterface;
+use React\EventLoop\TimerInterface;
 use React\Http\Io\ReadableBodyStream;
+use React\Http\Io\Sender;
 use React\Http\Io\Transaction;
 use React\Http\Message\Request;
 use React\Http\Message\Response;
@@ -13,6 +16,8 @@
 use React\EventLoop\Loop;
 use React\Promise\Deferred;
 use React\Promise\Promise;
+use React\Promise\PromiseInterface;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 use function React\Async\await;
@@ -24,12 +29,12 @@ class TransactionTest extends TestCase
     public function testWithOptionsReturnsNewInstanceWithChangedOption()
     {
         $sender = $this->makeSenderMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $transaction = new Transaction($sender, $loop);
 
         $new = $transaction->withOptions(['followRedirects' => false]);
 
-        $this->assertInstanceOf('React\Http\Io\Transaction', $new);
+        $this->assertInstanceOf(Transaction::class, $new);
         $this->assertNotSame($transaction, $new);
 
         $ref = new \ReflectionProperty($new, 'followRedirects');
@@ -41,7 +46,7 @@ public function testWithOptionsReturnsNewInstanceWithChangedOption()
     public function testWithOptionsDoesNotChangeOriginalInstance()
     {
         $sender = $this->makeSenderMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $transaction = new Transaction($sender, $loop);
 
         $transaction->withOptions(['followRedirects' => false]);
@@ -55,7 +60,7 @@ public function testWithOptionsDoesNotChangeOriginalInstance()
     public function testWithOptionsNullValueReturnsNewInstanceWithDefaultOption()
     {
         $sender = $this->makeSenderMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $transaction = new Transaction($sender, $loop);
 
         $transaction = $transaction->withOptions(['followRedirects' => false]);
@@ -69,34 +74,34 @@ public function testWithOptionsNullValueReturnsNewInstanceWithDefaultOption()
 
     public function testTimeoutExplicitOptionWillStartTimeoutTimer()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->anything())->willReturn($timer);
         $loop->expects($this->never())->method('cancelTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutImplicitFromIniWillStartTimeoutTimer()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->anything())->willReturn($timer);
         $loop->expects($this->never())->method('cancelTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
 
@@ -105,24 +110,24 @@ public function testTimeoutImplicitFromIniWillStartTimeoutTimer()
         $promise = $transaction->send($request);
         ini_set('default_socket_timeout', $old);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutExplicitOptionWillRejectWhenTimerFires()
     {
         $timeout = null;
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->callback(function ($cb) use (&$timeout) {
             $timeout = $cb;
             return true;
         }))->willReturn($timer);
         $loop->expects($this->never())->method('cancelTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
@@ -136,42 +141,42 @@ public function testTimeoutExplicitOptionWillRejectWhenTimerFires()
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Request timed out after 2 seconds', $exception->getMessage());
     }
 
     public function testTimeoutExplicitOptionWillNotStartTimeoutWhenSenderResolvesImmediately()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->never())->method('addTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(200, [], '');
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 0.001]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
         $promise->then($this->expectCallableOnceWith($response));
     }
 
     public function testTimeoutExplicitOptionWillCancelTimeoutTimerWhenSenderResolvesLaterOn()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(200, [], '');
 
         $deferred = new Deferred();
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn($deferred->promise());
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn($deferred->promise());
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 0.001]);
@@ -179,41 +184,41 @@ public function testTimeoutExplicitOptionWillCancelTimeoutTimerWhenSenderResolve
 
         $deferred->resolve($response);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
         $promise->then($this->expectCallableOnceWith($response));
     }
 
     public function testTimeoutExplicitOptionWillNotStartTimeoutWhenSenderRejectsImmediately()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->never())->method('addTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $exception = new \RuntimeException();
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(reject($exception));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(reject($exception));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 0.001]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
         $promise->then(null, $this->expectCallableOnceWith($exception));
     }
 
     public function testTimeoutExplicitOptionWillCancelTimeoutTimerWhenSenderRejectsLaterOn()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
         $deferred = new Deferred();
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn($deferred->promise());
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn($deferred->promise());
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 0.001]);
@@ -222,49 +227,49 @@ public function testTimeoutExplicitOptionWillCancelTimeoutTimerWhenSenderRejects
         $exception = new \RuntimeException();
         $deferred->reject($exception);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
         $promise->then(null, $this->expectCallableOnceWith($exception));
     }
 
     public function testTimeoutExplicitNegativeWillNotStartTimeoutTimer()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->never())->method('addTimer');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => -1]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutExplicitOptionWillNotStartTimeoutTimerWhenRequestBodyIsStreaming()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->never())->method('addTimer');
 
         $stream = new ThroughStream();
         $request = new Request('POST', 'http://example.com', [], new ReadableBodyStream($stream));
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutExplicitOptionWillStartTimeoutTimerWhenStreamingRequestBodyIsAlreadyClosed()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->anything())->willReturn($timer);
         $loop->expects($this->never())->method('cancelTimer');
 
@@ -272,28 +277,28 @@ public function testTimeoutExplicitOptionWillStartTimeoutTimerWhenStreamingReque
         $stream->close();
         $request = new Request('POST', 'http://example.com', [], new ReadableBodyStream($stream));
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
         $promise = $transaction->send($request);
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutExplicitOptionWillStartTimeoutTimerWhenStreamingRequestBodyClosesWhileSenderIsStillPending()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->anything())->willReturn($timer);
         $loop->expects($this->never())->method('cancelTimer');
 
         $stream = new ThroughStream();
         $request = new Request('POST', 'http://example.com', [], new ReadableBodyStream($stream));
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
@@ -301,20 +306,20 @@ public function testTimeoutExplicitOptionWillStartTimeoutTimerWhenStreamingReque
 
         $stream->close();
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
     public function testTimeoutExplicitOptionWillNotStartTimeoutTimerWhenStreamingRequestBodyClosesAfterSenderRejects()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->never())->method('addTimer');
 
         $stream = new ThroughStream();
         $request = new Request('POST', 'http://example.com', [], new ReadableBodyStream($stream));
 
         $deferred = new Deferred();
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn($deferred->promise());
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn($deferred->promise());
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
@@ -323,7 +328,7 @@ public function testTimeoutExplicitOptionWillNotStartTimeoutTimerWhenStreamingRe
         $deferred->reject(new \RuntimeException('Request failed'));
         $stream->close();
 
-        $this->assertInstanceOf('React\Promise\PromiseInterface', $promise);
+        $this->assertInstanceOf(PromiseInterface::class, $promise);
 
         $promise->then(null, $this->expectCallableOnce()); // avoid reporting unhandled rejection
     }
@@ -331,8 +336,8 @@ public function testTimeoutExplicitOptionWillNotStartTimeoutTimerWhenStreamingRe
     public function testTimeoutExplicitOptionWillRejectWhenTimerFiresAfterStreamingRequestBodyCloses()
     {
         $timeout = null;
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->with(2, $this->callback(function ($cb) use (&$timeout) {
             $timeout = $cb;
             return true;
@@ -342,8 +347,8 @@ public function testTimeoutExplicitOptionWillRejectWhenTimerFiresAfterStreamingR
         $stream = new ThroughStream();
         $request = new Request('POST', 'http://example.com', [], new ReadableBodyStream($stream));
 
-        $sender = $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(new Promise(function () { }));
+        $sender = $this->createMock(Sender::class);
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(new Promise(function () { }));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => 2]);
@@ -359,19 +364,19 @@ public function testTimeoutExplicitOptionWillRejectWhenTimerFiresAfterStreamingR
             $exception = $e;
         });
 
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Request timed out after 2 seconds', $exception->getMessage());
     }
 
     public function testReceivingErrorResponseWillRejectWithResponseException()
     {
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(404);
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['timeout' => -1]);
@@ -395,12 +400,12 @@ public function testReceivingStreamingBodyWillResolveWithBufferedResponseByDefau
             $stream->close();
         });
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(200, [], new ReadableBodyStream($stream));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, Loop::get());
         $promise = $transaction->send($request);
@@ -416,13 +421,13 @@ public function testReceivingStreamingBodyWithContentLengthExceedingMaximumRespo
         $stream = new ThroughStream();
         $stream->on('close', $this->expectCallableOnce());
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
         $response = new Response(200, ['Content-Length' => '100000000'], new ReadableBodyStream($stream, 100000000));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, Loop::get());
 
@@ -436,7 +441,7 @@ public function testReceivingStreamingBodyWithContentLengthExceedingMaximumRespo
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \OverflowException);
-        $this->assertInstanceOf('OverflowException', $exception);
+        $this->assertInstanceOf(\OverflowException::class, $exception);
         $this->assertEquals('Response body size of 100000000 bytes exceeds maximum of 16777216 bytes', $exception->getMessage());
         $this->assertEquals(defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90, $exception->getCode());
         $this->assertNull($exception->getPrevious());
@@ -447,13 +452,13 @@ public function testReceivingStreamingBodyWithContentsExceedingMaximumResponseBu
         $stream = new ThroughStream();
         $stream->on('close', $this->expectCallableOnce());
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
 
         $response = new Response(200, [], new ReadableBodyStream($stream));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, Loop::get());
         $transaction = $transaction->withOptions(['maximumSize' => 10]);
@@ -469,7 +474,7 @@ public function testReceivingStreamingBodyWithContentsExceedingMaximumResponseBu
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \OverflowException);
-        $this->assertInstanceOf('OverflowException', $exception);
+        $this->assertInstanceOf(\OverflowException::class, $exception);
         $this->assertEquals('Response body size exceeds maximum of 10 bytes', $exception->getMessage());
         $this->assertEquals(defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90, $exception->getCode());
         $this->assertNull($exception->getPrevious());
@@ -481,12 +486,12 @@ public function testReceivingStreamingBodyWillRejectWhenStreamEmitsError()
             throw new \UnexpectedValueException('Unexpected ' . $data, 42);
         });
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(200, [], new ReadableBodyStream($stream));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, Loop::get());
         $promise = $transaction->send($request);
@@ -501,25 +506,25 @@ public function testReceivingStreamingBodyWillRejectWhenStreamEmitsError()
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \RuntimeException);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Error while buffering response body: Unexpected Foo', $exception->getMessage());
         $this->assertEquals(42, $exception->getCode());
-        $this->assertInstanceOf('UnexpectedValueException', $exception->getPrevious());
+        $this->assertInstanceOf(\UnexpectedValueException::class, $exception->getPrevious());
     }
 
     public function testCancelBufferingResponseWillCloseStreamAndReject()
     {
-        $stream = $this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock();
+        $stream = $this->createMock(ReadableStreamInterface::class);
         $stream->expects($this->any())->method('isReadable')->willReturn(true);
         $stream->expects($this->once())->method('close');
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
+        $request = $this->createMock(RequestInterface::class);
         $response = new Response(200, [], new ReadableBodyStream($stream));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $deferred = new Deferred();
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn($deferred->promise());
+        $sender->expects($this->once())->method('send')->with($request)->willReturn($deferred->promise());
 
         $transaction = new Transaction($sender, Loop::get());
         $promise = $transaction->send($request);
@@ -533,7 +538,7 @@ public function testCancelBufferingResponseWillCloseStreamAndReject()
         });
 
         assert($exception instanceof \RuntimeException);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Cancelled buffering response body', $exception->getMessage());
         $this->assertEquals(0, $exception->getCode());
         $this->assertNull($exception->getPrevious());
@@ -541,14 +546,14 @@ public function testCancelBufferingResponseWillCloseStreamAndReject()
 
     public function testReceivingStreamingBodyWillResolveWithStreamingResponseIfStreamingIsEnabled()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
-        $request = $this->getMockBuilder('Psr\Http\Message\RequestInterface')->getMock();
-        $response = new Response(200, [], new ReadableBodyStream($this->getMockBuilder('React\Stream\ReadableStreamInterface')->getMock()));
+        $request = $this->createMock(RequestInterface::class);
+        $response = new Response(200, [], new ReadableBodyStream($this->createMock(ReadableStreamInterface::class)));
 
         // mock sender to resolve promise with the given $response in response to the given $request
         $sender = $this->makeSenderMock();
-        $sender->expects($this->once())->method('send')->with($this->equalTo($request))->willReturn(resolve($response));
+        $sender->expects($this->once())->method('send')->with($request)->willReturn(resolve($response));
 
         $transaction = new Transaction($sender, $loop);
         $transaction = $transaction->withOptions(['streaming' => true, 'timeout' => -1]);
@@ -566,7 +571,7 @@ public function testReceivingStreamingBodyWillResolveWithStreamingResponseIfStre
 
     public function testResponseCode304WithoutLocationWillResolveWithResponseAsIs()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         // conditional GET request will respond with 304 (Not Modified
         $request = new Request('GET', 'http://example.com', ['If-None-Match' => '"abc"']);
@@ -583,7 +588,7 @@ public function testResponseCode304WithoutLocationWillResolveWithResponseAsIs()
 
     public function testCustomRedirectResponseCode333WillFollowLocationHeaderAndSendRedirectedRequest()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         // original GET request will respond with custom 333 redirect status code and follow location header
         $requestOriginal = new Request('GET', 'http://example.com');
@@ -605,7 +610,7 @@ public function testCustomRedirectResponseCode333WillFollowLocationHeaderAndSend
 
     public function testFollowingRedirectWithSpecifiedHeaders()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = ['User-Agent' => 'Chrome'];
         $requestWithUserAgent = new Request('GET', 'http://example.com', $customHeaders);
@@ -635,7 +640,7 @@ public function testFollowingRedirectWithSpecifiedHeaders()
 
     public function testRemovingAuthorizationHeaderWhenChangingHostnamesDuringRedirect()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = ['Authorization' => 'secret'];
         $requestWithAuthorization = new Request('GET', 'http://example.com', $customHeaders);
@@ -665,7 +670,7 @@ public function testRemovingAuthorizationHeaderWhenChangingHostnamesDuringRedire
 
     public function testAuthorizationHeaderIsForwardedWhenRedirectingToSameDomain()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = ['Authorization' => 'secret'];
         $requestWithAuthorization = new Request('GET', 'http://example.com', $customHeaders);
@@ -695,7 +700,7 @@ public function testAuthorizationHeaderIsForwardedWhenRedirectingToSameDomain()
 
     public function testAuthorizationHeaderIsForwardedWhenLocationContainsAuthentication()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -725,7 +730,7 @@ public function testAuthorizationHeaderIsForwardedWhenLocationContainsAuthentica
 
     public function testSomeRequestHeadersShouldBeRemovedWhenRedirecting()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = [
             'Content-Type' => 'text/html; charset=utf-8',
@@ -760,7 +765,7 @@ public function testSomeRequestHeadersShouldBeRemovedWhenRedirecting()
 
     public function testRequestMethodShouldBeChangedWhenRedirectingWithSeeOther()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = [
             'Content-Type' => 'text/html; charset=utf-8',
@@ -796,7 +801,7 @@ public function testRequestMethodShouldBeChangedWhenRedirectingWithSeeOther()
 
     public function testRequestMethodAndBodyShouldNotBeChangedWhenRedirectingWith307Or308()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = [
             'Content-Type' => 'text/html; charset=utf-8',
@@ -839,7 +844,7 @@ public function testRequestMethodAndBodyShouldNotBeChangedWhenRedirectingWith307
 
     public function testRedirectingStreamingBodyWith307Or308ShouldThrowCantRedirectStreamException()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $customHeaders = [
             'Content-Type' => 'text/html; charset=utf-8',
@@ -874,7 +879,7 @@ public function testRedirectingStreamingBodyWith307Or308ShouldThrowCantRedirectS
 
     public function testCancelTransactionWillCancelRequest()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -892,8 +897,8 @@ public function testCancelTransactionWillCancelRequest()
 
     public function testCancelTransactionWillCancelTimeoutTimer()
     {
-        $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $timer = $this->createMock(TimerInterface::class);
+        $loop = $this->createMock(LoopInterface::class);
         $loop->expects($this->once())->method('addTimer')->willReturn($timer);
         $loop->expects($this->once())->method('cancelTimer')->with($timer);
 
@@ -914,7 +919,7 @@ public function testCancelTransactionWillCancelTimeoutTimer()
 
     public function testCancelTransactionWillCancelRedirectedRequest()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -941,7 +946,7 @@ public function testCancelTransactionWillCancelRedirectedRequest()
 
     public function testCancelTransactionWillCancelRedirectedRequestAgain()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -971,7 +976,7 @@ public function testCancelTransactionWillCancelRedirectedRequestAgain()
 
     public function testCancelTransactionWillCloseBufferingStream()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -994,7 +999,7 @@ public function testCancelTransactionWillCloseBufferingStream()
 
     public function testCancelTransactionWillCloseBufferingStreamAgain()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -1015,7 +1020,7 @@ public function testCancelTransactionWillCloseBufferingStreamAgain()
 
     public function testCancelTransactionShouldCancelSendingPromise()
     {
-        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop = $this->createMock(LoopInterface::class);
 
         $request = new Request('GET', 'http://example.com');
         $sender = $this->makeSenderMock();
@@ -1045,6 +1050,6 @@ public function testCancelTransactionShouldCancelSendingPromise()
      */
     private function makeSenderMock()
     {
-        return $this->getMockBuilder('React\Http\Io\Sender')->disableOriginalConstructor()->getMock();
+        return $this->createMock(Sender::class);
     }
 }
diff --git a/tests/Io/UploadedFileTest.php b/tests/Io/UploadedFileTest.php
index adbed51c..529b75af 100644
--- a/tests/Io/UploadedFileTest.php
+++ b/tests/Io/UploadedFileTest.php
@@ -8,14 +8,12 @@
 
 class UploadedFileTest extends TestCase
 {
-    public function failtyErrorProvider()
+    public static function failtyErrorProvider()
     {
-        return [
-            ['a'],
-            [null],
-            [-1],
-            [9]
-        ];
+        yield ['a'];
+        yield [null];
+        yield [-1];
+        yield [9];
     }
 
     /**
@@ -25,7 +23,8 @@ public function testFailtyError($error)
     {
         $stream = new BufferedBody('');
 
-        $this->setExpectedException('InvalidArgumentException', 'Invalid error code, must be an UPLOAD_ERR_* constant');
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid error code, must be an UPLOAD_ERR_* constant');
         new UploadedFile($stream, 0, $error, 'foo.bar', 'foo/bar');
     }
 
@@ -34,7 +33,8 @@ public function testNoMoveFile()
         $stream = new BufferedBody('');
         $uploadedFile = new UploadedFile($stream, 0, UPLOAD_ERR_OK, 'foo.bar', 'foo/bar');
 
-        $this->setExpectedException('RuntimeException', 'Not implemented');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Not implemented');
         $uploadedFile->moveTo('bar.foo');
     }
 
@@ -54,7 +54,8 @@ public function testGetStreamOnFailedUpload()
         $stream = new BufferedBody('');
         $uploadedFile = new UploadedFile($stream, 0, UPLOAD_ERR_NO_FILE, 'foo.bar', 'foo/bar');
 
-        $this->setExpectedException('RuntimeException', 'Cannot retrieve stream due to upload error');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Cannot retrieve stream due to upload error');
         $uploadedFile->getStream();
     }
 }
diff --git a/tests/Message/RequestTest.php b/tests/Message/RequestTest.php
index 543ddb88..148536a0 100644
--- a/tests/Message/RequestTest.php
+++ b/tests/Message/RequestTest.php
@@ -2,8 +2,10 @@
 
 namespace React\Tests\Http\Message;
 
+use Psr\Http\Message\StreamInterface;
 use React\Http\Io\HttpBodyStream;
 use React\Http\Message\Request;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 
@@ -33,8 +35,8 @@ public function testConstructWithStreamingRequestBodyReturnsBodyWhichImplementsR
         );
 
         $body = $request->getBody();
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
         $this->assertNull($body->getSize());
     }
 
@@ -52,7 +54,8 @@ public function testConstructWithHttpBodyStreamReturnsBodyAsIs()
 
     public function testConstructWithNullBodyThrows()
     {
-        $this->setExpectedException('InvalidArgumentException', 'Invalid request body given');
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid request body given');
         new Request(
             'GET',
             'http://localhost',
diff --git a/tests/Message/ResponseTest.php b/tests/Message/ResponseTest.php
index 61acf19e..6d4acb73 100644
--- a/tests/Message/ResponseTest.php
+++ b/tests/Message/ResponseTest.php
@@ -2,8 +2,10 @@
 
 namespace React\Tests\Http\Message;
 
+use Psr\Http\Message\StreamInterface;
 use React\Http\Io\HttpBodyStream;
 use React\Http\Message\Response;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 
@@ -15,7 +17,7 @@ public function testConstructWithStringBodyWillReturnStreamInstance()
         $body = $response->getBody();
 
         /** @var \Psr\Http\Message\StreamInterface $body */
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
         $this->assertEquals('hello', (string) $body);
     }
 
@@ -25,9 +27,9 @@ public function testConstructWithStreamingBodyWillReturnReadableBodyStream()
         $body = $response->getBody();
 
         /** @var \Psr\Http\Message\StreamInterface $body */
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
-        $this->assertInstanceof('React\Stream\ReadableStreamInterface', $body);
-        $this->assertInstanceOf('React\Http\Io\HttpBodyStream', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
+        $this->assertInstanceof(ReadableStreamInterface::class, $body);
+        $this->assertInstanceOf(HttpBodyStream::class, $body);
         $this->assertNull($body->getSize());
     }
 
@@ -44,13 +46,13 @@ public function testConstructWithHttpBodyStreamReturnsBodyAsIs()
 
     public function testFloatBodyWillThrow()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Response(200, [], 1.0);
     }
 
     public function testResourceBodyWillThrow()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Response(200, [], tmpfile());
     }
 
@@ -126,7 +128,8 @@ public function testJsonMethodReturnsJsonTextForSimpleString()
 
     public function testJsonMethodThrowsForInvalidString()
     {
-        $this->setExpectedException('InvalidArgumentException', 'Unable to encode given data as JSON: Malformed UTF-8 characters, possibly incorrectly encoded');
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Unable to encode given data as JSON: Malformed UTF-8 characters, possibly incorrectly encoded');
         Response::json("Hello w\xF6rld!");
     }
 
@@ -220,25 +223,25 @@ public function testParseMessageWithHttp10SimpleOkResponseWithLegacyNewlines()
 
     public function testParseMessageWithInvalidHttpProtocolVersion12Throws()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Response::parseMessage("HTTP/1.2 200 OK\r\n");
     }
 
     public function testParseMessageWithInvalidHttpProtocolVersion2Throws()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Response::parseMessage("HTTP/2 200 OK\r\n");
     }
 
     public function testParseMessageWithInvalidStatusCodeUnderflowThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Response::parseMessage("HTTP/1.1 99 OK\r\n");
     }
 
     public function testParseMessageWithInvalidResponseHeaderFieldThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Response::parseMessage("HTTP/1.1 200 OK\r\nServer\r\n");
     }
 }
diff --git a/tests/Message/ServerRequestTest.php b/tests/Message/ServerRequestTest.php
index 36d20bfa..596ebf47 100644
--- a/tests/Message/ServerRequestTest.php
+++ b/tests/Message/ServerRequestTest.php
@@ -2,8 +2,10 @@
 
 namespace React\Tests\Http\Message;
 
+use Psr\Http\Message\StreamInterface;
 use React\Http\Io\HttpBodyStream;
 use React\Http\Message\ServerRequest;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 
@@ -302,8 +304,8 @@ public function testConstructWithStreamingRequestBodyReturnsBodyWhichImplementsR
         );
 
         $body = $request->getBody();
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
         $this->assertSame(0, $body->getSize());
     }
 
@@ -319,8 +321,8 @@ public function testConstructWithStreamingRequestBodyReturnsBodyWithSizeFromCont
         );
 
         $body = $request->getBody();
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
         $this->assertSame(100, $body->getSize());
     }
 
@@ -336,14 +338,14 @@ public function testConstructWithStreamingRequestBodyReturnsBodyWithSizeUnknownF
         );
 
         $body = $request->getBody();
-        $this->assertInstanceOf('Psr\Http\Message\StreamInterface', $body);
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
+        $this->assertInstanceOf(StreamInterface::class, $body);
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
         $this->assertNull($body->getSize());
     }
 
     public function testConstructWithFloatRequestBodyThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new ServerRequest(
             'GET',
             'http://localhost',
@@ -354,7 +356,7 @@ public function testConstructWithFloatRequestBodyThrows()
 
     public function testConstructWithResourceRequestBodyThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new ServerRequest(
             'GET',
             'http://localhost',
@@ -403,85 +405,85 @@ public function testParseMessageWithConnectMethodWithAuthorityFormRequestTarget(
 
     public function testParseMessageWithInvalidHttp11RequestWithoutHostThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\n", []);
     }
 
     public function testParseMessageWithInvalidHttpProtocolVersionThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.2\r\n", []);
     }
 
     public function testParseMessageWithInvalidProtocolThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / CUSTOM/1.1\r\n", []);
     }
 
     public function testParseMessageWithInvalidHostHeaderWithoutValueThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost\r\n", []);
     }
 
     public function testParseMessageWithInvalidHostHeaderSyntaxThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: ///\r\n", []);
     }
 
     public function testParseMessageWithInvalidHostHeaderWithSchemeThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: http://localhost\r\n", []);
     }
 
     public function testParseMessageWithInvalidHostHeaderWithQueryThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: localhost?foo\r\n", []);
     }
 
     public function testParseMessageWithInvalidHostHeaderWithFragmentThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: localhost#foo\r\n", []);
     }
 
     public function testParseMessageWithInvalidContentLengthHeaderThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: localhost\r\nContent-Length:\r\n", []);
     }
 
     public function testParseMessageWithInvalidTransferEncodingHeaderThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: localhost\r\nTransfer-Encoding:\r\n", []);
     }
 
     public function testParseMessageWithInvalidBothContentLengthHeaderAndTransferEncodingHeaderThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET / HTTP/1.1\r\nHost: localhost\r\nContent-Length: 0\r\nTransfer-Encoding: chunked\r\n", []);
     }
 
     public function testParseMessageWithInvalidEmptyHostHeaderWithAbsoluteFormRequestTargetThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET http://example.com/ HTTP/1.1\r\nHost: \r\n", []);
     }
 
     public function testParseMessageWithInvalidConnectMethodNotUsingAuthorityFormThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("CONNECT / HTTP/1.1\r\nHost: localhost\r\n", []);
     }
 
     public function testParseMessageWithInvalidRequestTargetAsteriskFormThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         ServerRequest::parseMessage("GET * HTTP/1.1\r\nHost: localhost\r\n", []);
     }
 }
diff --git a/tests/Message/UriTest.php b/tests/Message/UriTest.php
index cdbc5a87..adaee94b 100644
--- a/tests/Message/UriTest.php
+++ b/tests/Message/UriTest.php
@@ -9,118 +9,116 @@ class UriTest extends TestCase
 {
     public function testCtorWithInvalidSyntaxThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Uri('///');
     }
 
     public function testCtorWithInvalidSchemeThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Uri('not+a+scheme://localhost');
     }
 
     public function testCtorWithInvalidHostThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Uri('http://not a host/');
     }
 
     public function testCtorWithInvalidPortThrows()
     {
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         new Uri('http://localhost:80000/');
     }
 
     public static function provideValidUris()
     {
-        return [
-            [
-                'http://localhost'
-            ],
-            [
-                'http://localhost/'
-            ],
-            [
-                'http://localhost:8080/'
-            ],
-            [
-                'http://127.0.0.1/'
-            ],
-            [
-                'http://[::1]:8080/'
-            ],
-            [
-                'http://localhost/path'
-            ],
-            [
-                'http://localhost/sub/path'
-            ],
-            [
-                'http://localhost/with%20space'
-            ],
-            [
-                'http://localhost/with%2fslash'
-            ],
-            [
-                'http://localhost/?name=Alice'
-            ],
-            [
-                'http://localhost/?name=John+Doe'
-            ],
-            [
-                'http://localhost/?name=John%20Doe'
-            ],
-            [
-                'http://localhost/?name=Alice&age=42'
-            ],
-            [
-                'http://localhost/?name=Alice&'
-            ],
-            [
-                'http://localhost/?choice=A%26B'
-            ],
-            [
-                'http://localhost/?safe=Yes!?'
-            ],
-            [
-                'http://localhost/?alias=@home'
-            ],
-            [
-                'http://localhost/?assign:=true'
-            ],
-            [
-                'http://localhost/?name='
-            ],
-            [
-                'http://localhost/?name'
-            ],
-            [
-                ''
-            ],
-            [
-                '/'
-            ],
-            [
-                '/path'
-            ],
-            [
-                'path'
-            ],
-            [
-                'http://user@localhost/'
-            ],
-            [
-                'http://user:@localhost/'
-            ],
-            [
-                'http://:pass@localhost/'
-            ],
-            [
-                'http://user:pass@localhost/path?query#fragment'
-            ],
-            [
-                'http://user%20name:pass%20word@localhost/path%20name?query%20name#frag%20ment'
-            ]
+        yield [
+            'http://localhost'
+        ];
+        yield [
+            'http://localhost/'
+        ];
+        yield [
+            'http://localhost:8080/'
+        ];
+        yield [
+            'http://127.0.0.1/'
+        ];
+        yield [
+            'http://[::1]:8080/'
+        ];
+        yield [
+            'http://localhost/path'
+        ];
+        yield [
+            'http://localhost/sub/path'
+        ];
+        yield [
+            'http://localhost/with%20space'
+        ];
+        yield [
+            'http://localhost/with%2fslash'
+        ];
+        yield [
+            'http://localhost/?name=Alice'
+        ];
+        yield [
+            'http://localhost/?name=John+Doe'
+        ];
+        yield [
+            'http://localhost/?name=John%20Doe'
+        ];
+        yield [
+            'http://localhost/?name=Alice&age=42'
+        ];
+        yield [
+            'http://localhost/?name=Alice&'
+        ];
+        yield [
+            'http://localhost/?choice=A%26B'
+        ];
+        yield [
+            'http://localhost/?safe=Yes!?'
+        ];
+        yield [
+            'http://localhost/?alias=@home'
+        ];
+        yield [
+            'http://localhost/?assign:=true'
+        ];
+        yield [
+            'http://localhost/?name='
+        ];
+        yield [
+            'http://localhost/?name'
+        ];
+        yield [
+            ''
+        ];
+        yield [
+            '/'
+        ];
+        yield [
+            '/path'
+        ];
+        yield [
+            'path'
+        ];
+        yield [
+            'http://user@localhost/'
+        ];
+        yield [
+            'http://user:@localhost/'
+        ];
+        yield [
+            'http://:pass@localhost/'
+        ];
+        yield [
+            'http://user:pass@localhost/path?query#fragment'
+        ];
+        yield [
+            'http://user%20name:pass%20word@localhost/path%20name?query%20name#frag%20ment'
         ];
     }
 
@@ -137,35 +135,33 @@ public function testToStringReturnsOriginalUriGivenToCtor($string)
 
     public static function provideValidUrisThatWillBeTransformed()
     {
-        return [
-            [
-                'http://localhost:8080/?',
-                'http://localhost:8080/'
-            ],
-            [
-                'http://localhost:8080/#',
-                'http://localhost:8080/'
-            ],
-            [
-                'http://localhost:8080/?#',
-                'http://localhost:8080/'
-            ],
-            [
-                'http://@localhost:8080/',
-                'http://localhost:8080/'
-            ],
-            [
-                'http://localhost:8080/?percent=50%',
-                'http://localhost:8080/?percent=50%25'
-            ],
-            [
-                'http://user name:pass word@localhost/path name?query name#frag ment',
-                'http://user%20name:pass%20word@localhost/path%20name?query%20name#frag%20ment'
-            ],
-            [
-                'HTTP://USER:PASS@LOCALHOST:8080/PATH?QUERY#FRAGMENT',
-                'http://USER:PASS@localhost:8080/PATH?QUERY#FRAGMENT'
-            ]
+        yield [
+            'http://localhost:8080/?',
+            'http://localhost:8080/'
+        ];
+        yield [
+            'http://localhost:8080/#',
+            'http://localhost:8080/'
+        ];
+        yield [
+            'http://localhost:8080/?#',
+            'http://localhost:8080/'
+        ];
+        yield [
+            'http://@localhost:8080/',
+            'http://localhost:8080/'
+        ];
+        yield [
+            'http://localhost:8080/?percent=50%',
+            'http://localhost:8080/?percent=50%25'
+        ];
+        yield [
+            'http://user name:pass word@localhost/path name?query name#frag ment',
+            'http://user%20name:pass%20word@localhost/path%20name?query%20name#frag%20ment'
+        ];
+        yield [
+            'HTTP://USER:PASS@LOCALHOST:8080/PATH?QUERY#FRAGMENT',
+            'http://USER:PASS@localhost:8080/PATH?QUERY#FRAGMENT'
         ];
     }
 
@@ -251,7 +247,7 @@ public function testWithSchemeThrowsWhenSchemeIsInvalid()
     {
         $uri = new Uri('http://localhost');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $uri->withScheme('invalid+scheme');
     }
 
@@ -375,7 +371,7 @@ public function testWithHostThrowsWhenHostIsInvalidWithPlus()
     {
         $uri = new Uri('http://localhost');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $uri->withHost('invalid+host');
     }
 
@@ -383,7 +379,7 @@ public function testWithHostThrowsWhenHostIsInvalidWithSpace()
     {
         $uri = new Uri('http://localhost');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $uri->withHost('invalid host');
     }
 
@@ -448,7 +444,7 @@ public function testWithPortThrowsWhenPortIsInvalidUnderflow()
     {
         $uri = new Uri('http://localhost');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $uri->withPort(0);
     }
 
@@ -456,7 +452,7 @@ public function testWithPortThrowsWhenPortIsInvalidOverflow()
     {
         $uri = new Uri('http://localhost');
 
-        $this->setExpectedException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         $uri->withPort(65536);
     }
 
@@ -576,112 +572,110 @@ public function testWithFragmentReturnsSameInstanceWhenFragmentIsUnchangedEncode
 
     public static function provideResolveUris()
     {
-        return [
-            [
-                'http://localhost/',
-                '',
-                'http://localhost/'
-            ],
-            [
-                'http://localhost/',
-                'http://example.com/',
-                'http://example.com/'
-            ],
-            [
-                'http://localhost/',
-                'path',
-                'http://localhost/path'
-            ],
-            [
-                'http://localhost/',
-                'path/',
-                'http://localhost/path/'
-            ],
-            [
-                'http://localhost/',
-                'path//',
-                'http://localhost/path/'
-            ],
-            [
-                'http://localhost',
-                'path',
-                'http://localhost/path'
-            ],
-            [
-                'http://localhost/a/b',
-                '/path',
-                'http://localhost/path'
-            ],
-            [
-                'http://localhost/',
-                '/a/b/c',
-                'http://localhost/a/b/c'
-            ],
-            [
-                'http://localhost/a/path',
-                'b/c',
-                'http://localhost/a/b/c'
-            ],
-            [
-                'http://localhost/a/path',
-                '/b/c',
-                'http://localhost/b/c'
-            ],
-            [
-                'http://localhost/a/path/',
-                'b/c',
-                'http://localhost/a/path/b/c'
-            ],
-            [
-                'http://localhost/a/path/',
-                '../b/c',
-                'http://localhost/a/b/c'
-            ],
-            [
-                'http://localhost',
-                '../../../a/b',
-                'http://localhost/a/b'
-            ],
-            [
-                'http://localhost/path',
-                '?query',
-                'http://localhost/path?query'
-            ],
-            [
-                'http://localhost/path',
-                '#fragment',
-                'http://localhost/path#fragment'
-            ],
-            [
-                'http://localhost/path',
-                'http://localhost',
-                'http://localhost'
-            ],
-            [
-                'http://localhost/path',
-                'http://localhost/?query#fragment',
-                'http://localhost/?query#fragment'
-            ],
-            [
-                'http://localhost/path/?a#fragment',
-                '?b',
-                'http://localhost/path/?b'
-            ],
-            [
-                'http://localhost/path',
-                '//localhost',
-                'http://localhost'
-            ],
-            [
-                'http://localhost/path',
-                '//localhost/a?query',
-                'http://localhost/a?query'
-            ],
-            [
-                'http://localhost/path',
-                '//LOCALHOST',
-                'http://localhost'
-            ]
+        yield [
+            'http://localhost/',
+            '',
+            'http://localhost/'
+        ];
+        yield [
+            'http://localhost/',
+            'http://example.com/',
+            'http://example.com/'
+        ];
+        yield [
+            'http://localhost/',
+            'path',
+            'http://localhost/path'
+        ];
+        yield [
+            'http://localhost/',
+            'path/',
+            'http://localhost/path/'
+        ];
+        yield [
+            'http://localhost/',
+            'path//',
+            'http://localhost/path/'
+        ];
+        yield [
+            'http://localhost',
+            'path',
+            'http://localhost/path'
+        ];
+        yield [
+            'http://localhost/a/b',
+            '/path',
+            'http://localhost/path'
+        ];
+        yield [
+            'http://localhost/',
+            '/a/b/c',
+            'http://localhost/a/b/c'
+        ];
+        yield [
+            'http://localhost/a/path',
+            'b/c',
+            'http://localhost/a/b/c'
+        ];
+        yield [
+            'http://localhost/a/path',
+            '/b/c',
+            'http://localhost/b/c'
+        ];
+        yield [
+            'http://localhost/a/path/',
+            'b/c',
+            'http://localhost/a/path/b/c'
+        ];
+        yield [
+            'http://localhost/a/path/',
+            '../b/c',
+            'http://localhost/a/b/c'
+        ];
+        yield [
+            'http://localhost',
+            '../../../a/b',
+            'http://localhost/a/b'
+        ];
+        yield [
+            'http://localhost/path',
+            '?query',
+            'http://localhost/path?query'
+        ];
+        yield [
+            'http://localhost/path',
+            '#fragment',
+            'http://localhost/path#fragment'
+        ];
+        yield [
+            'http://localhost/path',
+            'http://localhost',
+            'http://localhost'
+        ];
+        yield [
+            'http://localhost/path',
+            'http://localhost/?query#fragment',
+            'http://localhost/?query#fragment'
+        ];
+        yield [
+            'http://localhost/path/?a#fragment',
+            '?b',
+            'http://localhost/path/?b'
+        ];
+        yield [
+            'http://localhost/path',
+            '//localhost',
+            'http://localhost'
+        ];
+        yield [
+            'http://localhost/path',
+            '//localhost/a?query',
+            'http://localhost/a?query'
+        ];
+        yield [
+            'http://localhost/path',
+            '//LOCALHOST',
+            'http://localhost'
         ];
     }
 
diff --git a/tests/Middleware/LimitConcurrentRequestsMiddlewareTest.php b/tests/Middleware/LimitConcurrentRequestsMiddlewareTest.php
index b79826d6..67656d4c 100644
--- a/tests/Middleware/LimitConcurrentRequestsMiddlewareTest.php
+++ b/tests/Middleware/LimitConcurrentRequestsMiddlewareTest.php
@@ -10,6 +10,7 @@
 use React\Promise\Deferred;
 use React\Promise\Promise;
 use React\Promise\PromiseInterface;
+use React\Stream\ReadableStreamInterface;
 use React\Stream\ThroughStream;
 use React\Tests\Http\TestCase;
 
@@ -114,7 +115,8 @@ public function testThrowsExceptionDirectlyFromMiddlewareWhenBelowLimit()
     {
         $middleware = new LimitConcurrentRequestsMiddleware(1);
 
-        $this->setExpectedException('RuntimeException', 'demo');
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('demo');
         $middleware(new ServerRequest('GET', 'https://example.com/'), function () {
             throw new \RuntimeException('demo');
         });
@@ -124,7 +126,8 @@ public function testThrowsErrorDirectlyFromMiddlewareWhenBelowLimit()
     {
         $middleware = new LimitConcurrentRequestsMiddleware(1);
 
-        $this->setExpectedException('Error', 'demo');
+        $this->expectException(\Error::class);
+        $this->expectExceptionMessage('demo');
         $middleware(new ServerRequest('GET', 'https://example.com/'), function () {
             throw new \Error('demo');
         });
@@ -159,7 +162,7 @@ public function testReturnsPendingPromiseFromMiddlewareWhenAboveLimit()
 
     public function testStreamDoesNotPauseOrResumeWhenBelowLimit()
     {
-        $body = $this->getMockBuilder('React\Http\Io\HttpBodyStream')->disableOriginalConstructor()->getMock();
+        $body = $this->createMock(HttpBodyStream::class);
         $body->expects($this->never())->method('pause');
         $body->expects($this->never())->method('resume');
         $limitHandlers = new LimitConcurrentRequestsMiddleware(1);
@@ -168,7 +171,7 @@ public function testStreamDoesNotPauseOrResumeWhenBelowLimit()
 
     public function testStreamDoesPauseWhenAboveLimit()
     {
-        $body = $this->getMockBuilder('React\Http\Io\HttpBodyStream')->disableOriginalConstructor()->getMock();
+        $body = $this->createMock(HttpBodyStream::class);
         $body->expects($this->once())->method('pause');
         $body->expects($this->never())->method('resume');
         $limitHandlers = new LimitConcurrentRequestsMiddleware(1);
@@ -182,7 +185,7 @@ public function testStreamDoesPauseWhenAboveLimit()
 
     public function testStreamDoesPauseAndThenResumeWhenDequeued()
     {
-        $body = $this->getMockBuilder('React\Http\Io\HttpBodyStream')->disableOriginalConstructor()->getMock();
+        $body = $this->createMock(HttpBodyStream::class);
         $body->expects($this->once())->method('pause');
         $body->expects($this->once())->method('resume');
         $limitHandlers = new LimitConcurrentRequestsMiddleware(1);
@@ -467,11 +470,11 @@ public function testReceivesStreamingBodyChangesInstanceWithCustomBodyButSameDat
         $deferred->reject(new \RuntimeException());
 
         $this->assertNotSame($request, $req);
-        $this->assertInstanceOf('Psr\Http\Message\ServerRequestInterface', $req);
+        $this->assertInstanceOf(ServerRequestInterface::class, $req);
 
         $body = $req->getBody();
-        $this->assertInstanceOf('React\Stream\ReadableStreamInterface', $body);
-        /* @var $body \React\Stream\ReadableStreamInterface */
+        $this->assertInstanceOf(ReadableStreamInterface::class, $body);
+        /* @var $body ReadableStreamInterface */
 
         $this->assertEquals(5, $body->getSize());
 
diff --git a/tests/Middleware/RequestBodyBufferMiddlewareTest.php b/tests/Middleware/RequestBodyBufferMiddlewareTest.php
index 262ad9ca..28866c96 100644
--- a/tests/Middleware/RequestBodyBufferMiddlewareTest.php
+++ b/tests/Middleware/RequestBodyBufferMiddlewareTest.php
@@ -272,7 +272,7 @@ function (ServerRequestInterface $request) {
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \RuntimeException);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Buffered 3', $exception->getMessage());
         $this->assertEquals(42, $exception->getCode());
         $this->assertNull($exception->getPrevious());
@@ -307,7 +307,7 @@ function (ServerRequestInterface $request) {
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \Error);
-        $this->assertInstanceOf('Error', $exception);
+        $this->assertInstanceOf(\Error::class, $exception);
         $this->assertEquals('Buffered 3', $exception->getMessage());
         $this->assertEquals(42, $exception->getCode());
         $this->assertNull($exception->getPrevious());
@@ -342,10 +342,10 @@ public function testBufferingRejectsWhenStreamEmitsError()
         $this->assertFalse($stream->isWritable());
 
         assert($exception instanceof \RuntimeException);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Error while buffering request body: Unexpected Foo', $exception->getMessage());
         $this->assertEquals(42, $exception->getCode());
-        $this->assertInstanceOf('UnexpectedValueException', $exception->getPrevious());
+        $this->assertInstanceOf(\UnexpectedValueException::class, $exception->getPrevious());
     }
 
     public function testFullBodyStreamedBeforeCallingNextMiddleware()
@@ -399,7 +399,7 @@ public function testCancelBufferingClosesStreamAndRejectsPromise()
         });
 
         assert($exception instanceof \RuntimeException);
-        $this->assertInstanceOf('RuntimeException', $exception);
+        $this->assertInstanceOf(\RuntimeException::class, $exception);
         $this->assertEquals('Cancelled buffering request body', $exception->getMessage());
         $this->assertEquals(0, $exception->getCode());
         $this->assertNull($exception->getPrevious());
diff --git a/tests/TestCase.php b/tests/TestCase.php
index fa6fcd1c..4df6087f 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -2,6 +2,7 @@
 
 namespace React\Tests\Http;
 
+use PHPUnit\Framework\MockObject\MockBuilder;
 use PHPUnit\Framework\TestCase as BaseTestCase;
 
 class TestCase extends BaseTestCase
@@ -39,46 +40,12 @@ protected function expectCallableNever()
 
     protected function createCallableMock()
     {
-        if (method_exists('PHPUnit\Framework\MockObject\MockBuilder', 'addMethods')) {
+        if (method_exists(MockBuilder::class, 'addMethods')) {
             // PHPUnit 9+
-            return $this->getMockBuilder('stdClass')->addMethods(['__invoke'])->getMock();
+            return $this->getMockBuilder(\stdClass::class)->addMethods(['__invoke'])->getMock();
         } else {
-            // legacy PHPUnit 4 - PHPUnit 8
-            return $this->getMockBuilder('stdClass')->setMethods(['__invoke'])->getMock();
+            // legacy PHPUnit
+            return $this->getMockBuilder(\stdClass::class)->setMethods(['__invoke'])->getMock();
         }
     }
-
-    public function assertContainsString($needle, $haystack)
-    {
-        if (method_exists($this, 'assertStringContainsString')) {
-            // PHPUnit 7.5+
-            $this->assertStringContainsString($needle, $haystack);
-        } else {
-            // legacy PHPUnit 4 - PHPUnit 7.5
-            $this->assertContains($needle, $haystack);
-        }
-    }
-
-    public function assertNotContainsString($needle, $haystack)
-    {
-        if (method_exists($this, 'assertStringNotContainsString')) {
-            // PHPUnit 7.5+
-            $this->assertStringNotContainsString($needle, $haystack);
-        } else {
-            // legacy PHPUnit 4 - PHPUnit 7.5
-            $this->assertNotContains($needle, $haystack);
-        }
-    }
-
-    public function setExpectedException($exception, $exceptionMessage = '', $exceptionCode = null)
-    {
-        $this->expectException($exception);
-        if ($exceptionMessage !== '') {
-            $this->expectExceptionMessage($exceptionMessage);
-        }
-        if ($exceptionCode !== null) {
-            $this->expectExceptionCode($exceptionCode);
-        }
-    }
-
 }