2026년 Laravel 테스트: Pest 5, TIA, 모킹 및 기술 면접 질문

use Illuminate\Foundation\Testing\RefreshDatabase;

pest()
    ->extend(Tests\TestCase::class)
    ->use(RefreshDatabase::class)
    ->in('Feature');

use App\Models\User;

it('registers a new user with valid data', function () {
    $response = $this->postJson('/api/register', [
        'name' => 'Jane Doe',
        'email' => 'jane@example.com',
        'password' => 'SecurePass123!',
        'password_confirmation' => 'SecurePass123!',
    ]);

    $response->assertStatus(201)
        ->assertJsonStructure(['user' => ['id', 'name', 'email']]);

    expect(User::where('email', 'jane@example.com')->exists())->toBeTrue();
});

# 첫 번째 실행: 베이스라인 기록 (PCOV 또는 Xdebug 필요)
php artisan test

# 이후 실행: 영향받는 테스트만 실행
php artisan test

use App\Services\PriceCalculator;

describe('PriceCalculator', function () {
    it('applies a percentage discount correctly', function () {
        $calculator = new PriceCalculator();

        // 150.00 기본 가격에서 20% 할인
        $result = $calculator->applyDiscount(150.00, 20);

        expect($result)->toBe(120.00);
    });

    it('rejects negative discount values', function () {
        $calculator = new PriceCalculator();

        expect(fn () => $calculator->applyDiscount(100.00, -5))
            ->toThrow(InvalidArgumentException::class);
    });
});

use App\Models\Order;
use App\Models\User;
use Illuminate\Support\Facades\Mail;
use Illuminate\Support\Facades\Queue;
use App\Mail\OrderConfirmation;
use App\Jobs\ProcessPayment;

it('dispatches payment job and sends confirmation email', function () {
    // Mail과 Queue 파사드 모두 페이크
    Mail::fake();
    Queue::fake();

    $user = User::factory()->create();
    $order = Order::factory()->for($user)->create([
        'total' => 99.99,
        'status' => 'pending',
    ]);

    // Act: HTTP를 통해 주문 확인
    $this->actingAs($user)
        ->postJson("/api/orders/{$order->id}/confirm")
        ->assertOk();

    // Assert: 결제 잡이 올바른 금액으로 디스패치됨
    Queue::assertPushed(ProcessPayment::class, function ($job) use ($order) {
        return $job->order->id === $order->id
            && $job->order->total === 99.99;
    });

    // Assert: 확인 이메일이 사용자에게 전송됨
    Mail::assertSent(OrderConfirmation::class, function ($mail) use ($user) {
        return $mail->hasTo($user->email);
    });
});

use App\Services\PaymentGateway;
use App\Services\StripeClient;

it('charges the customer through the payment gateway', function () {
    // Stripe 클라이언트 모킹 생성
    $stripeClient = Mockery::mock(StripeClient::class);
    $stripeClient->shouldReceive('charge')
        ->once()
        ->with('cus_abc123', 5000, 'usd')
        ->andReturn(['status' => 'succeeded', 'id' => 'ch_xyz']);

    // 컨테이너에 모킹 바인딩
    $this->app->instance(StripeClient::class, $stripeClient);

    $gateway = app(PaymentGateway::class);
    $result = $gateway->processCharge('cus_abc123', 50.00);

    expect($result['status'])->toBe('succeeded');
});

arch('controllers do not use Eloquent directly')
    ->expect('App\Http\Controllers')
    ->not->toUse('Illuminate\Database\Eloquent');

arch('services are final classes')
    ->expect('App\Services')
    ->toBeFinal();

arch('no debugging functions in production code')
    ->expect(['dd', 'dump', 'var_dump', 'ray'])
    ->not->toBeUsed();

arch()->preset()->laravel();
arch()->preset()->security();
arch()->preset()->php();

# 특정 클래스에 대해 뮤테이션 테스트 실행
php artisan test --mutate --class=App\\Services\\PriceCalculator

// 예: 높은 커버리지지만 낮은 뮤테이션 점수를 가진 테스트
it('calculates shipping cost', function () {
    $cost = calculateShipping(weight: 5.0, zone: 'domestic');

    // 결과가 숫자인지만 확인
    expect($cost)->toBeFloat();
});

// 개선됨: 정확한 값을 어설트하여 뮤테이션 포착
it('calculates domestic shipping for 5kg package', function () {
    $cost = calculateShipping(weight: 5.0, zone: 'domestic');

    // 정확한 어설션이 연산자와 값 뮤테이션을 포착
    expect($cost)->toBe(12.50);
});

use App\Models\Article;
use App\Models\User;

it('publishes a draft article and updates the timestamp', function () {
    $author = User::factory()->create(['role' => 'editor']);

    $article = Article::factory()
        ->for($author, 'author')
        ->draft()
        ->create(['title' => 'Testing Best Practices']);

    $this->actingAs($author)
        ->patchJson("/api/articles/{$article->id}/publish")
        ->assertOk()
        ->assertJsonPath('data.status', 'published');

    $article->refresh();

    expect($article->status)->toBe('published')
        ->and($article->published_at)->not->toBeNull()
        ->and($article->published_at->isToday())->toBeTrue();
});

use App\Models\User;

describe('API Authentication', function () {
    it('rejects unauthenticated requests with 401', function () {
        $this->getJson('/api/profile')
            ->assertUnauthorized();
    });

    it('returns the authenticated user profile', function () {
        $user = User::factory()->create([
            'name' => 'John Doe',
            'email' => 'john@example.com',
        ]);

        $this->actingAs($user)
            ->getJson('/api/profile')
            ->assertOk()
            ->assertJson([
                'data' => [
                    'name' => 'John Doe',
                    'email' => 'john@example.com',
                ],
            ]);
    });

    it('validates required fields on registration', function () {
        $this->postJson('/api/register', [])
            ->assertUnprocessable()
            ->assertJsonValidationErrors(['name', 'email', 'password']);
    });
});