name: acc-testing-knowledge description: Testing knowledge base for PHP 8.5 projects. Provides testing pyramid, AAA pattern, naming conventions, isolation principles, DDD testing guidelines, and PHPUnit patterns.

Testing Knowledge Base

Quick reference for PHP testing patterns, principles, and best practices.

Testing Pyramid

        /\
       /  \     Functional (10%)
      /────\    - E2E, browser tests
     /      \   - Slow, fragile
    /────────\  Integration (20%)
   /          \ - DB, HTTP, queues
  /────────────\Unit (70%)
 /              \- Fast, isolated
/________________\- Business logic

Rule: 70% unit, 20% integration, 10% functional. Invert the pyramid = slow, brittle test suite.

AAA Pattern (Arrange-Act-Assert)

public function test_order_calculates_total_with_discount(): void
{
    // Arrange — set up test data
    $order = new Order(OrderId::generate());
    $order->addItem(new Product('Book', Money::EUR(100)));
    $discount = new PercentageDiscount(10);

    // Act — execute the behavior
    $total = $order->calculateTotal($discount);

    // Assert — verify the outcome
    self::assertEquals(Money::EUR(90), $total);
}

Rules:

• One blank line between sections
• Single Act per test
• Assert behavior, not implementation

Naming Conventions

PHPUnit Style

test_{method}_{scenario}_{expected}

Pest Style

it('calculates total with discount applied')
it('throws exception when confirming shipped order')
it('fails validation for invalid email format')

Test Isolation Principles

DO

• Fresh fixtures per test
• Independent test execution (any order)
• Teardown cleans all state
• Use in-memory implementations

DON'T

• Shared mutable state between tests
• Tests depending on execution order
• Global variables or singletons
• Real external services in unit tests

Quick Quality Checklist

DDD Component Testing

PHP 8.5 Test Patterns

Unit Test Template

<?php

declare(strict_types=1);

namespace Tests\Unit\Domain;

use PHPUnit\Framework\Attributes\CoversClass;
use PHPUnit\Framework\Attributes\Group;
use PHPUnit\Framework\TestCase;

#[Group('unit')]
#[CoversClass(Email::class)]
final class EmailTest extends TestCase
{
    public function test_creates_valid_email(): void
    {
        $email = new Email('user@example.com');

        self::assertSame('user@example.com', $email->value);
    }

    public function test_throws_for_invalid_format(): void
    {
        $this->expectException(InvalidArgumentException::class);

        new Email('invalid');
    }
}

Integration Test Template

<?php

declare(strict_types=1);

namespace Tests\Integration\Infrastructure;

use PHPUnit\Framework\Attributes\Group;
use Tests\DatabaseTestCase;

#[Group('integration')]
final class DoctrineOrderRepositoryTest extends DatabaseTestCase
{
    private OrderRepositoryInterface $repository;

    protected function setUp(): void
    {
        parent::setUp();
        $this->repository = $this->getContainer()->get(OrderRepositoryInterface::class);
    }

    public function test_saves_and_retrieves_order(): void
    {
        // Arrange
        $order = OrderMother::pending();

        // Act
        $this->repository->save($order);
        $found = $this->repository->findById($order->id());

        // Assert
        self::assertNotNull($found);
        self::assertTrue($order->id()->equals($found->id()));
    }
}

Test Doubles Quick Reference

Decision Matrix

Need to verify a call was made?
├── Yes → Mock or Spy
└── No → Need real behavior?
    ├── Yes → Fake
    └── No → Stub

Common Test Smells

References

For detailed information, load these reference files:

• references/unit-testing.md — Unit test patterns and examples
• references/integration-testing.md — Integration test setup and patterns
• references/ddd-testing.md — Testing DDD components (VO, Entity, Aggregate, Service)