Update Factorial Methods + Factorial Test + ReadMe.md

README.md

@@ -37,11 +37,17 @@ $result = BaseConvert::convert('FF', 16, '0123456789ABCDEF')->to(10, 'ZYXWVUTSRQ
 ```php
 use Graphita\Mathematics\Factorial;
 
-// Factrorial 3 : 3x2x1
-$result = (new Factorial(3))->calculate(); // 6
+// Factorial 3 : 3x2x1
+$result = Factorial::instance(3)->calculate()->getResult(); // 6
 
-// Factrorial 4 : 4x3x2x1
-$result = (new Factorial(4))->calculate(); // 24
+// Factorial 4 : 4x3x2x1
+$result = Factorial::instance(4)->calculate()->getResult(); // 24
+
+// Factorial 5 : 5x4x3x2x1
+$factorial = new Factorial;
+$factorial->setNumber(5);
+$factorial->calculate();
+$result = $factorial->getResult();
 ```
 
 ### Permutation

src/Factorial.php

@@ -3,6 +3,8 @@
 namespace Graphita\Mathematics;
 
 use InvalidArgumentException;
+use function PHPUnit\Framework\isEmpty;
+use function PHPUnit\Framework\isNull;
 
 class Factorial
 {
@@ -12,29 +14,57 @@ class Factorial
  private int $number;
 
  /**
- * @param $number
+ * @var ?int
  */
- public function __construct($number)
+ private ?int $result = null;
+
+ /**
+ * @param int|null $number
+ * @return Factorial
+ */
+ public static function instance(int $number = null): Factorial
  {
- if (!is_integer($number)) {
- throw new InvalidArgumentException('Number must be a Positive Integer to Calculate Factorial !');
+ $instance = new static();
+ if (is_integer($number)) {
+ $instance->setNumber($number);
  }
+ return $instance;
+ }
+
+ /**
+ * @param int $number
+ * @return Factorial
+ */
+ public function setNumber(int $number): static
+ {
  if ($number < 0) {
  throw new InvalidArgumentException('Number must be a Positive Integer to Calculate Factorial !');
  }
  $this->number = $number;
+
+ return $this;
  }
 
  /**
- * @return int
+ * @return $this
  */
- public function calculate(): int
+ public function calculate(): static
  {
- $result = 1;
- while ($this->number > 1) {
- $result *= $this->number;
- $this->number--;
+ $number = $this->number;
+ $this->result = 1;
+ while ($number > 1) {
+ $this->result *= $number;
+ $number--;
  }
- return $result;
+
+ return $this;
+ }
+
+ /**
+ * @return int|null
+ */
+ public function getResult(): ?int
+ {
+ return $this->result;
  }
 }

tests/FactorialTest.php

@@ -7,54 +7,63 @@
 
 class FactorialTest extends TestCase
 {
- public function testWithNonIntegerNumber()
- {
- $this->expectException(\InvalidArgumentException::class);
- $this->expectExceptionMessage('Number must be a Positive Integer to Calculate Factorial !');
-
- $result = (new Factorial(2.5))->calculate();
- }
-
  public function testWithNegativeNumber()
  {
  $this->expectException(\InvalidArgumentException::class);
  $this->expectExceptionMessage('Number must be a Positive Integer to Calculate Factorial !');
 
- $result = (new Factorial(-2))->calculate();
+ $result = Factorial::instance(-2)->calculate()->getResult();
  }
 
  public function testFactorialZero()
  {
- $result = (new Factorial(0))->calculate();
+ $result = Factorial::instance(0)->calculate()->getResult();
 
  $this->assertEquals(1, $result);
  }
 
  public function testFactorialOne()
  {
- $result = (new Factorial(1))->calculate();
+ $result = Factorial::instance(1)->calculate()->getResult();
 
  $this->assertEquals(1, $result);
  }
 
  public function testFactorialTwo()
  {
- $result = (new Factorial(2))->calculate();
+ $result = Factorial::instance(2)->calculate()->getResult();
 
  $this->assertEquals(2, $result);
  }
 
  public function testFactorialThree()
  {
- $result = (new Factorial(3))->calculate();
+ $result = Factorial::instance(3)->calculate()->getResult();
 
  $this->assertEquals(2 * 3, $result);
  }
 
  public function testFactorialTen()
  {
- $result = (new Factorial(10))->calculate();
+ $result = Factorial::instance(10)->calculate()->getResult();
 
  $this->assertEquals(2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10, $result);
  }
+
+ public function testSetNumber()
+ {
+ $factorial = new Factorial();
+ $factorial->setNumber(4);
+ $factorial->calculate();
+ $result = $factorial->getResult();
+
+ $this->assertEquals(2 * 3 * 4, $result);
+ }
+
+ public function testGetResultBeforeCalculate()
+ {
+ $result = Factorial::instance(3)->getResult();
+
+ $this->assertNull($result);
+ }
 }