php-standard

PHP & Testing Standards

Language-specific rules for PHP projects covering strict typing, PSR compliance, clean architecture, and PHPUnit testing conventions.

When to Activate

• Writing or modifying PHP code (>= 8.2)
• Creating or updating PHPUnit tests
• Reviewing PHP code for standards compliance
• Setting up PHP project architecture

Core Concepts

• Strict typing everywhere — declare(strict_types=1) in every file
• PSR compliance — PSR-12 coding style, PSR-4 autoloading
• Value Objects — domain concepts modeled as immutable objects
• TDD flow — one test at a time, written before the implementation

Detailed Guidance

Environment & Constraints

• PHP Version: Target >= 8.2. Use modern features (Readonly properties, Enums, Constructor Promotion) where applicable.
• Strict Typing: Always include declare(strict_types=1); at the top of every file.
• PSR Standards: Adhere strictly to PSR-12 (Coding Style) and PSR-4 (Autoloading).

Clean Code & Architecture

• Method Size: Methods must be between 10 and 20 lines max.
• Abstractions: Use Value Objects for domain concepts (Email, Price, Id).
• Inversion of Control: Dependencies must be injected via constructor, preferably using promoted properties.

Testing Protocol (PHPUnit)

• Framework: PHPUnit.
• TDD Flow: Create exactly one test before implementing the logic.
• Naming: test[FunctionName]_[Scenario]_[ExpectedResult].
• Structure: Use Given-When-Then comments.

Test Maintainability

• Object Mother: Use for complex entities.
• Data Providers: Use @dataProvider to keep tests DRY when testing multiple cases.
• Location: tests/ mirroring src/.

Recursive Verification

• Autoloading: Check composer.json or directory structure to ensure correct namespaces.
• Type Tracing: If a method returns a class, peek into that class to understand its structure before using the return value.

Examples

Test structure:

public function testCreateUser_WithValidData_ReturnsUser(): void
{
    // Given
    $email = EmailMother::random();
    // When
    $user = $this->service->create($email);
    // Then
    $this->assertEquals($email, $user->email());
}