Writing Testable Symfony Apps

Do you struggle as soon as you want to test a controller or a repository? Do you feel like it's sometimes impossible to write unit tests for a Symfony application? In this talk, I will show you design patterns that will not only make testing your Symfony applications trivial, but will also make your code a pleasure to work with.

Transcript

1. Writing Testable
   Symfony Apps
   SYMFONY WORLD ONLINE | JUN, 2022 @afilina
   

   View Slide

2. “Our tests are slow.“
   “We can’t really write unit tests.”
   “Tests are hard to maintain.”
   

   View Slide

3. Anna Filina
   • Coding since 1997
   • PHP since 2003
   • Legacy archaeology
   • Test automation
   • Public speaking
   • Mentorship
   • YouTube videos
   

   View Slide

4. class MyController extends AbstractController
   {
   public function index(): Response
   {
   return $this->render('my/index.html.twig', [
   'variable' => 'value',
   ]);
   }
   }
   

   View Slide

5. class MyControllerTest extends TestCase
   {
   public function testIndex(): void
   {
   $controller = new MyController();
   $controller->index();
   }
   }
   

   View Slide

6. Error : Call to a member function has() on null
   ./vendor/symfony/framework-bundle/Controller/AbstractController.php:254
   ./vendor/symfony/framework-bundle/Controller/AbstractController.php:266
   ./src/Controller/MyController.php:14
   ./tests/Controller/MyControllerTest.php:25
   

   View Slide

7. class MyController extends AbstractController
   {
   public function index(): Response
   {
   return $this->render('my/index.html.twig', [
   'variable' => 'value',
   ]);
   }
   }
   

   View Slide

8. use Twig\Environment;
   class MyTestableController
   {
   public function __construct(private Environment $twig)
   {
   }
   public function index(): Response
   {
   $html = $this->twig->render('my/index.html.twig', [
   'var' => 'value',
   ]);
   return new Response($html);
   }
   }
   

   View Slide

9. services:
   App\Controller\:
   resource: '../src/Controller/'
   tags: ['controller.service_arguments']
   

   View Slide

10. public function testIndex(): void
    {
    $controller = new MyTestableController(
    $twig = $this->createMock(Environment::class)
    );
    $twig
    ->method('render')
    ->with('my/index.html.twig', ['var' => 'value'])
    ->willReturn('some content');
    self::assertEquals(
    'some content',
    $controller->index()->getContent()
    );
    }
    

    View Slide

11. Time: 00:00.089, Memory: 10.00 MB
    OK (1 test, 1 assertion)
    

    View Slide

12. Unit Integration
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

13. Unit Integration
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

14. Unit Integration
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

15. Unit Integration
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

16. MyController
    Address
    AddressRepository
    GET /saved-addresses
    routes.php
    

    View Slide

17. # Behat feature file
    Scenario: Buyer can purchase using a credit card
    Given I selected a product
    When I submit a valid credit card
    Then I should see a payment receipt
    afilina.com/learn
    

    View Slide

18. • Routes
    • Service container
    • Security
    • Cache, Twig and other packages
    

    View Slide

19. UI
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

20. UI
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

21. UI
    MyController
    Address
    AddressRepository
    routes.php
    

    View Slide

22. AddressRepository
    Access database
    Map records to classes
    

    View Slide

23. if ($address->isBilling() && $address->getCountry() !== 'Canada') {
    //...
    }
    

    View Slide

24. View Slide

25. View Slide

26. Doctrine Entities
    

    View Slide

27. View Slide

28. View Slide

29. View Slide

30. SubscriptionRenewal
    Mocked
    PaymentProvider
    

    View Slide

31. SubscriptionRenewal
    Mocked
    PaymentProvider
    

    View Slide

32. SubscriptionRenewal
    Real
    PaymentProvider
    

    View Slide

33. SubscriptionRenewal
    Real
    PaymentProvider
    

    View Slide

34. cardToken
    amount
    description
    ChargeRequest
    

    View Slide

35. final class ChargeRequest
    {
    public function __construct(
    readonly public string $token,
    readonly public int $amount,
    readonly public string $description
    ) {}
    }
    

    View Slide

36. SubscriptionRenewal PaymentProvider
    

    View Slide

37. SubscriptionRenewal PaymentProvider
    

    View Slide

38. final class ChargeRequest
    {
    public function __construct(
    readonly public string $token,
    readonly public int $amount,
    readonly public string $description
    ) {
    if ($amount < 0) {
    throw new \DomainException('Amount cannot be lower than 0');
    }
    }
    }
    

    View Slide

39. Isn’t that overkill for an edge case?
    

    View Slide

40. • Avoid extending framework classes
    • Use multiple test types in tandem (pyramid)
    • Extract business logic from infrastructure
    • Use small immutable classes
    

    View Slide

41. @afilina
    Questions?
    

    View Slide