diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a82d7f6..9aff974 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,9 +13,9 @@ jobs:
     runs-on: [ubuntu-18.04]
     strategy:
       matrix:
-        php: [7.2]
+        php: ['7.2', '7.4', '8.0', '8.1']
     steps:
-      - name: Setup PHP
+      - name: Setup PHP (PHP ${{ matrix.php }})
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
@@ -24,9 +24,10 @@ jobs:
       - uses: actions/checkout@v1
       - name: Install Composer dependencies
         run: composer install
-      - name: Coding standard
+      - uses: symfonycorp/security-checker-action@v3
+      - name: Coding standard (PHP ${{ matrix.php }})
         run: php${{ matrix.php }} ./vendor/bin/ecs check src tests
-      - name: PHPUnit tests
+      - name: PHPUnit tests (PHP ${{ matrix.php }})
         run: php${{ matrix.php }} ./vendor/bin/phpunit --testdox --verbose --stop-on-failure
       - name: Code coverage
         run: php${{ matrix.php }} -d xdebug.mode=coverage ./vendor/bin/phpunit --coverage-clover=var/coverage.xml
@@ -36,8 +37,5 @@ jobs:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: ./var/coverage.xml
           fail_ci_if_error: true
-      - name: Upload coverage to Scrutinizer
-        run: |
-          wget https://scrutinizer-ci.com/ocular.phar
-          cp var/coverage.xml var/coverage.clover
-          php${{ matrix.php }} ocular.phar code-coverage:upload --access-token="${{ secrets.SCRUTINIZER_TOKEN }}" --format=php-clover var/coverage.clover
+      - name: Display the vulnerabilities as JSON
+        run: echo ${{ steps.security-check.outputs.vulns }}
diff --git a/.gitignore b/.gitignore
index 2516f29..f3a104c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ vendor
 composer.lock
 tests-api/.env
 var/
+.phpunit.result.cache
diff --git a/composer.json b/composer.json
index f6ced46..677517d 100644
--- a/composer.json
+++ b/composer.json
@@ -35,7 +35,7 @@
     "php": "^7.2|^8.0"
   },
   "require-dev": {
-    "omnipay/tests": "^3",
+    "omnipay/tests": "^4",
     "symplify/easy-coding-standard": "^10.2",
     "symfony/var-dumper": "^5.4"
   }
diff --git a/ecs.php b/ecs.php
index 160ac3a..d77d062 100644
--- a/ecs.php
+++ b/ecs.php
@@ -7,7 +7,7 @@
 use Symplify\EasyCodingStandard\ValueObject\Option;
 use Symplify\EasyCodingStandard\ValueObject\Set\SetList;
 
-return static function (ECSConfig $ecsConfig): void {
+return static function(ECSConfig $ecsConfig): void {
     $parameters = $ecsConfig->parameters();
     $parameters->set(Option::PATHS, [
         __DIR__ . '/src',
diff --git a/src/Message/CompletePurchaseRequest.php b/src/Message/CompletePurchaseRequest.php
index caaeb0f..c89f5c0 100644
--- a/src/Message/CompletePurchaseRequest.php
+++ b/src/Message/CompletePurchaseRequest.php
@@ -37,7 +37,7 @@ public function sendData($data)
 
         $responseData = json_decode($httpResponse->getBody()->getContents(), true);
 
-        return $this->response = new CompletePurchaseResponse($this, $responseData, $this->getEndpoint());
+        return $this->response = new CompletePurchaseResponse($this, $responseData);
     }
 
     private function generateSignature(): string
diff --git a/src/Message/RefundsResponse.php b/src/Message/RefundsResponse.php
index c674c74..fb73199 100644
--- a/src/Message/RefundsResponse.php
+++ b/src/Message/RefundsResponse.php
@@ -21,7 +21,7 @@ public function __construct(RequestInterface $request, $data)
         }
     }
 
-    public function getRefunds(): array
+    public function getRefunds(): ?array
     {
         return $this->refunds;
     }
diff --git a/tests/GatewayTest.php b/tests/GatewayTest.php
index adeb3fc..6bfbbd9 100644
--- a/tests/GatewayTest.php
+++ b/tests/GatewayTest.php
@@ -22,7 +22,7 @@ class GatewayTest extends GatewayTestCase
      */
     protected $gateway;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/CardCharge3dsRequestTest.php b/tests/Message/CardCharge3dsRequestTest.php
index b706979..1639c77 100644
--- a/tests/Message/CardCharge3dsRequestTest.php
+++ b/tests/Message/CardCharge3dsRequestTest.php
@@ -16,7 +16,7 @@ class CardCharge3dsRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->request = new CardCharge3dsRequest($this->getHttpClient(), $this->getHttpRequest());
         $this->request->initialize([