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
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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 test-pack 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\Core\Bridge\Symfony\Bundle\Test\ApiTestCase;
use App\Entity\Book;
use Hautelook\AliceBundle\PhpUnit\RefreshDatabaseTrait;

class BooksTest extends ApiTestCase
{
    // This trait provided by HautelookAliceBundle 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' => [],
        ]);
        $this->assertRegExp('~^/books/\d+$~', $response->toArray()['@id']);
        $this->assertMatchesResourceItemJsonSchema(Book::class);
    }

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

        $this->assertResponseStatusCodeSame(400);
        $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 = static::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 = static::findIriBy(Book::class, ['isbn' => '9781344037075']);

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

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

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.

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

$ docker-compose exec php vendor/bin/simple-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):