Writing Your First Test

Your First PHPUnit Test

// src/Calculator.php
class Calculator {
    public function add(int $a, int $b): int       { return $a + $b; }
    public function divide(int $a, int $b): float  {
        if ($b === 0) throw new DivisionByZeroError("Cannot divide by zero");
        return $a / $b;
    }
}

// tests/Unit/CalculatorTest.php
use PHPUnitFrameworkTestCase;

class CalculatorTest extends TestCase {
    private Calculator $calc;

    protected function setUp(): void {
        $this->calc = new Calculator();
    }

    public function testAddReturnsCorrectSum(): void {
        $this->assertEquals(5, $this->calc->add(2, 3));
        $this->assertEquals(0, $this->calc->add(-1, 1));
    }

    public function testDivideByZeroThrowsException(): void {
        $this->expectException(DivisionByZeroError::class);
        $this->expectExceptionMessage("Cannot divide by zero");
        $this->calc->divide(10, 0);
    }
}

// Run
./vendor/bin/phpunit tests/Unit/CalculatorTest.php