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acc-create-unit-test

Generates PHPUnit unit tests for PHP 8.5. Creates isolated tests with AAA pattern, proper naming, attributes, and one behavior per test. Supports Value Objects, Entities, Services.

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SKILL.md

Unit Test Generator

Generates PHPUnit 11+ unit tests for PHP 8.5 classes.

Characteristics

  • Isolated — no external dependencies (DB, HTTP, filesystem)
  • Fast — executes in <100ms
  • Focused — one behavior per test
  • AAA Pattern — Arrange-Act-Assert structure
  • Self-documenting — descriptive test names

Template

php
<?php

declare(strict_types=1);

namespace Tests\Unit\{Namespace};

use {FullyQualifiedClassName};
use PHPUnit\Framework\Attributes\CoversClass;
use PHPUnit\Framework\Attributes\Group;
use PHPUnit\Framework\TestCase;

#[Group('unit')]
#[CoversClass({ClassName}::class)]
final class {ClassName}Test extends TestCase
{
    private {ClassName} $sut;

    protected function setUp(): void
    {
        $this->sut = new {ClassName}(/* dependencies */);
    }

    public function test_{method}_{scenario}_{expected}(): void
    {
        // Arrange
        {arrange_code}

        // Act
        {act_code}

        // Assert
        {assert_code}
    }
}

Naming Convention

test_{method}_{scenario}_{expected}
Part Description Example
{method} Method under test calculate_total
{scenario} Input condition with_discount
{expected} Expected outcome returns_reduced_price

Examples:

php
test_confirm_when_pending_changes_status_to_confirmed
test_create_with_invalid_email_throws_exception
test_equals_with_same_value_returns_true
test_add_item_increases_total

Test Patterns by Component

Value Object Tests

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

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

    // Validation - invalid
    public function test_throws_for_empty_value(): void
    {
        $this->expectException(InvalidArgumentException::class);

        new Email('');
    }

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

        new Email('not-an-email');
    }

    // Equality
    public function test_equals_returns_true_for_same_value(): void
    {
        $email1 = new Email('user@example.com');
        $email2 = new Email('user@example.com');

        self::assertTrue($email1->equals($email2));
    }

    public function test_equals_returns_false_for_different_value(): void
    {
        $email1 = new Email('user@example.com');
        $email2 = new Email('other@example.com');

        self::assertFalse($email1->equals($email2));
    }
}

Entity Tests

php
#[Group('unit')]
#[CoversClass(Order::class)]
final class OrderTest extends TestCase
{
    private Order $order;

    protected function setUp(): void
    {
        $this->order = new Order(
            OrderId::fromString('order-123'),
            CustomerId::fromString('customer-456')
        );
    }

    // Identity
    public function test_has_unique_identity(): void
    {
        self::assertSame('order-123', $this->order->id()->toString());
    }

    // Initial state
    public function test_is_pending_when_created(): void
    {
        self::assertTrue($this->order->isPending());
    }

    // State transitions - valid
    public function test_confirm_changes_status_to_confirmed(): void
    {
        $this->order->addItem(ProductMother::book(), 1);

        $this->order->confirm();

        self::assertTrue($this->order->isConfirmed());
    }

    // State transitions - invalid
    public function test_confirm_throws_when_already_confirmed(): void
    {
        $this->order->addItem(ProductMother::book(), 1);
        $this->order->confirm();

        $this->expectException(DomainException::class);

        $this->order->confirm();
    }

    // Business rules
    public function test_add_item_increases_total(): void
    {
        $this->order->addItem(ProductMother::withPrice(Money::EUR(100)), 2);

        self::assertEquals(Money::EUR(200), $this->order->total());
    }

    // Domain events
    public function test_records_order_confirmed_event(): void
    {
        $this->order->addItem(ProductMother::book(), 1);

        $this->order->confirm();

        $events = $this->order->releaseEvents();
        self::assertCount(1, $events);
        self::assertInstanceOf(OrderConfirmedEvent::class, $events[0]);
    }
}

Domain Service Tests

php
#[Group('unit')]
#[CoversClass(TransferMoneyService::class)]
final class TransferMoneyServiceTest extends TestCase
{
    private TransferMoneyService $service;
    private InMemoryAccountRepository $repository;
    private CollectingEventDispatcher $dispatcher;

    protected function setUp(): void
    {
        $this->repository = new InMemoryAccountRepository();
        $this->dispatcher = new CollectingEventDispatcher();
        $this->service = new TransferMoneyService(
            $this->repository,
            $this->dispatcher
        );
    }

    public function test_transfers_money_between_accounts(): void
    {
        // Arrange
        $source = AccountMother::withBalance(Money::EUR(1000));
        $target = AccountMother::withBalance(Money::EUR(500));
        $this->repository->save($source);
        $this->repository->save($target);

        // Act
        $this->service->transfer(
            $source->id(),
            $target->id(),
            Money::EUR(300)
        );

        // Assert
        $updatedSource = $this->repository->findById($source->id());
        $updatedTarget = $this->repository->findById($target->id());
        self::assertEquals(Money::EUR(700), $updatedSource->balance());
        self::assertEquals(Money::EUR(800), $updatedTarget->balance());
    }

    public function test_throws_for_insufficient_funds(): void
    {
        // Arrange
        $source = AccountMother::withBalance(Money::EUR(100));
        $target = AccountMother::withBalance(Money::EUR(500));
        $this->repository->save($source);
        $this->repository->save($target);

        // Assert
        $this->expectException(InsufficientFundsException::class);

        // Act
        $this->service->transfer(
            $source->id(),
            $target->id(),
            Money::EUR(300)
        );
    }
}

Data Providers

php
use PHPUnit\Framework\Attributes\DataProvider;

#[DataProvider('validEmailsProvider')]
public function test_accepts_valid_formats(string $email): void
{
    $vo = new Email($email);

    self::assertSame($email, $vo->value);
}

public static function validEmailsProvider(): array
{
    return [
        'simple' => ['user@example.com'],
        'with subdomain' => ['user@mail.example.com'],
        'with plus' => ['user+tag@example.com'],
        'with dots' => ['first.last@example.com'],
    ];
}

#[DataProvider('invalidEmailsProvider')]
public function test_rejects_invalid_formats(string $email): void
{
    $this->expectException(InvalidArgumentException::class);

    new Email($email);
}

public static function invalidEmailsProvider(): array
{
    return [
        'empty' => [''],
        'no at' => ['userexample.com'],
        'no domain' => ['user@'],
        'spaces' => ['user @example.com'],
    ];
}

Generation Instructions

  1. Analyze the class:

    • Identify public methods
    • Identify dependencies (constructor parameters)
    • Identify value objects (final readonly)
    • Identify entities (has id, state changes)
    • Identify services (orchestrates, uses repositories)

  2. Determine test cases:

    • Happy path for each method
    • Edge cases (null, empty, boundary)
    • Exception paths (validation failures)
    • State transitions (for entities)

  3. Generate test class:

    • Match namespace: src/Domain/Order/Order.php → tests/Unit/Domain/Order/OrderTest.php
    • Add attributes: #[Group('unit')], #[CoversClass]
    • Create setUp if shared state needed

  4. Generate test methods:

    • Follow naming convention
    • Use AAA structure
    • One assertion group per test

  5. Add helpers if needed:

    • Use existing Mothers/Builders
    • Create inline builders for simple cases

Assertions Reference

php
// Value comparisons
self::assertSame($expected, $actual);      // ===
self::assertEquals($expected, $actual);    // ==
self::assertTrue($condition);
self::assertFalse($condition);
self::assertNull($value);
self::assertNotNull($value);

// Types
self::assertInstanceOf(ClassName::class, $object);

// Strings
self::assertStringContainsString($needle, $haystack);
self::assertStringStartsWith($prefix, $string);

// Arrays
self::assertCount($expected, $array);
self::assertContains($needle, $array);
self::assertArrayHasKey($key, $array);

// Exceptions
$this->expectException(ExceptionClass::class);
$this->expectExceptionMessage('message');
$this->expectExceptionCode(404);

Usage

Provide:

  • Path to class to test
  • Or class name and namespace
  • Specific methods to focus on (optional)

The generator will:

  1. Read the source class
  2. Analyze methods and dependencies
  3. Generate comprehensive test class
  4. Include happy path + edge cases + exceptions

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