Testing the API

Now that you have a functional API, you should write tests to ensure it has no bugs, and to prevent future regressions. Some would argue that it’s even better to write tests first.

API Platform provides a set of helpful testing utilities to write unit tests, functional tests, and to create test fixtures.

Let’s learn how to use them!

Tests and Assertions screencast
Watch the Tests & Assertions screencast

In this article you’ll learn how to use:

PHPUnit, a testing framework to cover your classes with unit tests and to write API-oriented functional tests thanks to its API Platform and Symfony integrations.
DoctrineFixturesBundle, a bundle to load data fixtures in the database.
Foundry, an expressive fixtures generator to write data fixtures.

# Creating Data Fixtures

Before creating your functional tests, you will need a dataset to pre-populate your API and be able to test it.

First, install Foundry and Doctrine/DoctrineFixturesBundle:

docker compose exec php \
    composer require --dev foundry orm-fixtures

Thanks to Symfony Flex, DoctrineFixturesBundle and Foundry are ready to use!

Then, create some factories for the bookstore API you created in the tutorial:

docker compose exec php \
    bin/console make:factory 'App\Entity\Book'
docker compose exec php \
    bin/console make:factory 'App\Entity\Review'

Improve the default values:

// src/Factory/BookFactory.php

    // ...

    protected function getDefaults(): array
    {
        return [
            'author' => self::faker()->name(),
            'description' => self::faker()->text(),
            'isbn' => self::faker()->isbn13(),
            'publication_date' => \DateTimeImmutable::createFromMutable(self::faker()->dateTime()),
            'title' => self::faker()->sentence(4),
        ];
    }

// src/Factory/ReviewFactory.php
// ...
use function Zenstruck\Foundry\lazy;

    // ...

    protected function getDefaults(): array
    {
        return [
            'author' => self::faker()->name(),
            'body' => self::faker()->text(),
            'book' => lazy(fn() => BookFactory::randomOrCreate()),
            'publicationDate' => \DateTimeImmutable::createFromMutable(self::faker()->dateTime()),
            'rating' => self::faker()->numberBetween(0, 5),
        ];
    }

Create some stories:

docker compose exec php \
    bin/console make:story 'DefaultBooks'
docker compose exec php \
    bin/console make:story 'DefaultReviews'

// src/Story/DefaultBooksStory.php

namespace App\Story;

use App\Factory\BookFactory;
use Zenstruck\Foundry\Story;

final class DefaultBooksStory extends Story
{
    public function build(): void
    {
        BookFactory::createMany(100);
    }
}

// src/Story/DefaultReviewsStory.php

namespace App\Story;

use App\Factory\ReviewFactory;
use Zenstruck\Foundry\Story;

final class DefaultReviewsStory extends Story
{
    public function build(): void
    {
        ReviewFactory::createMany(200);
    }
}

Edit your Fixtures:

//src/DataFixtures/AppFixtures.php

namespace App\DataFixtures;

use App\Story\DefaultBooksStory;
use App\Story\DefaultReviewsStory;
use Doctrine\Bundle\FixturesBundle\Fixture;
use Doctrine\Persistence\ObjectManager;

class AppFixtures extends Fixture
{
    public function load(ObjectManager $manager): void
    {
        DefaultBooksStory::load();
        DefaultReviewsStory::load();
    }
}

You can now load your fixtures in the database with the following command:

docker compose exec php \
    bin/console doctrine:fixtures:load

To learn more about fixtures, take a look at the documentation of Foundry. The list of available generators as well as a cookbook explaining how to create custom generators can be found in the documentation of Faker, the library used by Foundry under the hood.

# Writing Functional Tests

Now that you have some data fixtures for your API, you are ready to write functional tests with PHPUnit.

The API Platform test client implements the interfaces of the Symfony HttpClient. HttpClient is shipped with the API Platform distribution. The Symfony test pack, which includes PHPUnit as well as Symfony components useful for testing, is also included.

If you don’t use the distribution, run composer require --dev symfony/test-pack symfony/http-client to install them.

Install DAMADoctrineTestBundle to reset the database automatically before each test:

docker compose exec php \
    composer require --dev dama/doctrine-test-bundle

And activate it in the phpunit.xml.dist file:

<!-- api/phpunit.xml.dist -->
<phpunit>
    <!-- ... -->

    <extensions>
        <extension class="DAMA\DoctrineTestBundle\PHPUnit\PHPUnitExtension"/>
    </extensions>
</phpunit>

Optionally, you can install JSON Schema for PHP if you want to use the JSON Schema test assertions provided by API Platform:

docker compose exec php \
    composer require --dev justinrainbow/json-schema

Your API is now ready to be functionally tested. Create your test classes under the tests/ directory.

Here is an example of functional tests specifying the behavior of the bookstore API you created in the tutorial:

<?php
// api/tests/BooksTest.php

namespace App\Tests;

use ApiPlatform\Symfony\Bundle\Test\ApiTestCase;
use App\Entity\Book;
use App\Factory\BookFactory;
use Zenstruck\Foundry\Test\Factories;
use Zenstruck\Foundry\Test\ResetDatabase;

class BooksTest extends ApiTestCase
{
    // This trait provided by Foundry will take care of refreshing the database content to a known state before each test
    use ResetDatabase, Factories;

    public function testGetCollection(): void
    {
        // Create 100 books using our factory
        BookFactory::createMany(100);
    
        // The client implements Symfony HttpClient's `HttpClientInterface`, and the response `ResponseInterface`
        $response = static::createClient()->request('GET', '/books');

        $this->assertResponseIsSuccessful();
        // Asserts that the returned content type is JSON-LD (the default)
        $this->assertResponseHeaderSame('content-type', 'application/ld+json; charset=utf-8');

        // Asserts that the returned JSON is a superset of this one
        $this->assertJsonContains([
            '@context' => '/contexts/Book',
            '@id' => '/books',
            '@type' => 'hydra:Collection',
            'hydra:totalItems' => 100,
            'hydra:view' => [
                '@id' => '/books?page=1',
                '@type' => 'hydra:PartialCollectionView',
                'hydra:first' => '/books?page=1',
                'hydra:last' => '/books?page=4',
                'hydra:next' => '/books?page=2',
            ],
        ]);

        // Because test fixtures are automatically loaded between each test, you can assert on them
        $this->assertCount(30, $response->toArray()['hydra:member']);

        // Asserts that the returned JSON is validated by the JSON Schema generated for this resource by API Platform
        // This generated JSON Schema is also used in the OpenAPI spec!
        $this->assertMatchesResourceCollectionJsonSchema(Book::class);
    }

    public function testCreateBook(): void
    {
        $response = static::createClient()->request('POST', '/books', ['json' => [
            'isbn' => '0099740915',
            'title' => 'The Handmaid\'s Tale',
            'description' => 'Brilliantly conceived and executed, this powerful evocation of twenty-first century America gives full rein to Margaret Atwood\'s devastating irony, wit and astute perception.',
            'author' => 'Margaret Atwood',
            'publicationDate' => '1985-07-31T00:00:00+00:00',
        ]]);

        $this->assertResponseStatusCodeSame(201);
        $this->assertResponseHeaderSame('content-type', 'application/ld+json; charset=utf-8');
        $this->assertJsonContains([
            '@context' => '/contexts/Book',
            '@type' => 'Book',
            'isbn' => '0099740915',
            'title' => 'The Handmaid\'s Tale',
            'description' => 'Brilliantly conceived and executed, this powerful evocation of twenty-first century America gives full rein to Margaret Atwood\'s devastating irony, wit and astute perception.',
            'author' => 'Margaret Atwood',
            'publicationDate' => '1985-07-31T00:00:00+00:00',
            'reviews' => [],
        ]);
        $this->assertMatchesRegularExpression('~^/books/\d+$~', $response->toArray()['@id']);
        $this->assertMatchesResourceItemJsonSchema(Book::class);
    }

    public function testCreateInvalidBook(): void
    {
        static::createClient()->request('POST', '/books', ['json' => [
            'isbn' => 'invalid',
        ]]);

        $this->assertResponseStatusCodeSame(422);
        $this->assertResponseHeaderSame('content-type', 'application/ld+json; charset=utf-8');

        $this->assertJsonContains([
            '@context' => '/contexts/ConstraintViolationList',
            '@type' => 'ConstraintViolationList',
            'hydra:title' => 'An error occurred',
            'hydra:description' => 'isbn: This value is neither a valid ISBN-10 nor a valid ISBN-13.
title: This value should not be blank.
description: This value should not be blank.
author: This value should not be blank.
publicationDate: This value should not be null.',
        ]);
    }

    public function testUpdateBook(): void
    {
        // Only create the book we need with a given ISBN
        BookFactory::createOne(['isbn' => '9781344037075']);
    
        $client = static::createClient();
        // findIriBy allows to retrieve the IRI of an item by searching for some of its properties.
        $iri = $this->findIriBy(Book::class, ['isbn' => '9781344037075']);

        // Use the PATCH method here to do a partial update
        $client->request('PATCH', $iri, [
            'json' => [
                'title' => 'updated title',
            ],
            'headers' => [
                'Content-Type' => 'application/merge-patch+json',
            ]           
        ]);

        $this->assertResponseIsSuccessful();
        $this->assertJsonContains([
            '@id' => $iri,
            'isbn' => '9781344037075',
            'title' => 'updated title',
        ]);
    }

    public function testDeleteBook(): void
    {
        // Only create the book we need with a given ISBN
        BookFactory::createOne(['isbn' => '9781344037075']);

        $client = static::createClient();
        $iri = $this->findIriBy(Book::class, ['isbn' => '9781344037075']);

        $client->request('DELETE', $iri);

        $this->assertResponseStatusCodeSame(204);
        $this->assertNull(
            // Through the container, you can access all your services from the tests, including the ORM, the mailer, remote API clients...
            static::getContainer()->get('doctrine')->getRepository(Book::class)->findOneBy(['isbn' => '9781344037075'])
        );
    }
}

As you can see, the example uses the trait ResetDatabase from Foundry which will, at the beginning of each test, purge the database, begin a transaction, and, at the end of each test, roll back the transaction previously begun. Because of this, you can run your tests without worrying about fixtures.

There is one caveat though: in some tests, it is necessary to perform multiple requests in one test, for example when creating a user via the API and checking that a subsequent login using the same password works. However, the client will by default reboot the kernel, which will reset the database. You can prevent this by adding $client->disableReboot(); to such tests.

All you have to do now is to run your tests:

docker compose exec php \
    bin/phpunit

If everything is working properly, you should see OK (5 tests, 17 assertions). Your REST API is now properly tested!

Check out the testing documentation to discover the full range of assertions and other features provided by API Platform’s test utilities.

# Writing Unit Tests

In addition to integration tests written using the helpers provided by ApiTestCase, all the classes of your project should be covered by unit tests. To do so, learn how to write unit tests with PHPUnit and its Symfony/API Platform integration.

# Continuous Integration, Continuous Delivery and Continuous Deployment

Running your test suite in your CI/CD pipeline is important to ensure good quality and delivery time.

The API Platform distribution is shipped with a GitHub Actions workflow that builds the Docker images, does a smoke test to check that the application’s entrypoint is accessible, and runs PHPUnit.

The API Platform Demo contains a CD workflow that uses the Helm chart provided with the distribution to deploy the app on a Kubernetes cluster.

# Additional and Alternative Testing Tools

You may also be interested in these alternative testing tools (not included in the API Platform distribution):

Hoppscotch, create functional test for your API
Hoppscotch, create functional test for your API Platform project using a nice UI, benefit from its Swagger integration and run tests in the CI using the command-line tool;
Behat, a behavior-driven development (BDD) framework to write the API specification as user stories and in natural language then execute these scenarios against the application to validate its behavior;
Blackfire Player, a nice DSL to crawl HTTP services, assert responses, and extract data from HTML/XML/JSON responses;
PHP Matcher, the Swiss Army knife of JSON document testing.

# Using the API Platform Distribution for End-to-End Testing

If you would like to verify that your stack (including services such as the DBMS, web server, Varnish) works, you need end-to-end (E2E) testing. To do so, we recommend using Playwright if you use have PWA/JavaScript-heavy app, or Symfony Panther if you mostly use Twig.

Usually, E2E testing should be done with a production-like setup. For your convenience, you may run our Docker Compose setup for production locally.