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.
Alice and its Symfony integration, an expressive fixtures generator to write data fixtures.

Official Symfony recipes are provided for both tools.

# 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 Alice:

docker compose exec php \
    composer require --dev alice

Thanks to Symfony Flex, Alice (and AliceBundle) are ready to use! Place your data fixtures files in a directory named fixtures/.

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

# api/fixtures/books.yaml
App\Entity\Book:
    book_{1..100}:
        isbn: <isbn13()>
        title: <sentence(4)>
        description: <text()>
        author: <name()>
        publicationDate: <dateTime()>

# api/fixtures/reviews.yaml
App\Entity\Review:
    review_{1..200}:
        rating: <numberBetween(0, 5)>
        body: <text()>
        author: <name()>
        publicationDate: <dateTime()>
        book: '@book_*'

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

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

To learn more about fixtures, take a look at the documentation of Alice and AliceBundle. 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 Alice 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.

Install the Symfony test pack (which includes PHPUnit and PHPUnit Bridge), Symfony HttpClient (the API Platform test client is built on top of Symfony HttpClient, and allows to leverage all its features) and JSON Schema for PHP (used by API Platform to provide JSON Schema test assertions):

docker compose exec php \
    composer require --dev symfony/test-pack symfony/http-client justinrainbow/json-schema

Your API is 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 Hautelook\AliceBundle\PhpUnit\RefreshDatabaseTrait;

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

    public function testGetCollection(): void
    {
        // 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
    {
        $client = static::createClient();
        // findIriBy allows to retrieve the IRI of an item by searching for some of its properties.
        // ISBN 9786644879585 has been generated by Alice when loading test fixtures.
        // Because Alice use a seeded pseudo-random number generator, we're sure that this ISBN will always be generated.
        $iri = $this->findIriBy(Book::class, ['isbn' => '9781344037075']);

        $client->request('PUT', $iri, ['json' => [
            'title' => 'updated title',
        ]]);

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

    public function testDeleteBook(): void
    {
        $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'])
        );
    }

    public function testLogin(): void
    {
        $response = static::createClient()->request('POST', '/login', ['json' => [
            'email' => '[email protected]',
            'password' => 'admin',
        ]]);
        
        $this->assertResponseIsSuccessful();
    }
}

As you can see, the example uses the trait RefreshDatabaseTrait from AliceBundle which will, at the beginning of each test, purge the database, load fixtures, 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.

# Additional and Alternative Testing Tools

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

Behat and its Behatch extension, 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 (see example in API Platform Demo);
Postman tests (proprietary), create functional test for your API Platform project using a nice UI, benefit from the Swagger integration and run tests in the CI using newman;
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.

It is also useful to do a smoke test to check that your application is working; for example, that the application’s entrypoint is accessible. This could be used as a quick test after each Docker build to ensure that the Docker images are not broken.

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