PHPUnit

PHPUnit is the standard unit testing framework for the PHP ecosystem. Examples include usage in Laravel, Symfony, and WordPress.

When to Use

• PHP Application: The industry standard.
• TDD: Built-in support for mocking and code coverage.

Quick Start

<?php
use PHPUnit\Framework\TestCase;

final class StackTest extends TestCase
{
    public function testPushAndPop(): void
    {
        $stack = [];
        $this->assertEmpty($stack);

        array_push($stack, 'foo');
        $this->assertNotEmpty($stack);
        $this->assertEquals('foo', array_pop($stack));
    }
}

Core Concepts

Assertions

Methods like $this->assertTrue(), $this->assertSame(), $this->expectException().

Mock Objects

PHPUnit gives you control over the behavior of dependencies.

$stub = $this->createMock(SomeClass::class);
$stub->method('doSomething')->willReturn('foo');
$this->assertEquals('foo', $stub->doSomething());

Data Providers

Pass data to a test method (similar to parameterized tests).

#[DataProvider('additionProvider')]
public function testAdd(int $a, int $b, int $expected): void { ... }

Best Practices (2025)

Do:

• Use Strict Assertions: $this->assertSame() checks types (===), whereas assertEquals is loose (==). Strict is safer.
• Use Namespaces: Organize tests Tests\Unit\UserTest matching App\Models\User.
• PHPUnit 11 features: Use the new attributes #[Test] instead of /** @test */ annotations if on PHP 8.2+.

Don't:

• Don't test private methods: Test the public API. If a private method is complex, extract it to a new class.

References

• PHPUnit Documentation