Creating FunctionalTest for REST/JSON:APIfor Drupal 8 , 9 , 10 , and 11

In our previous lesson, we covered how to test your Drupal APIs using Postman and cURL. Now, we'll take a step further by creating automated functional tests for your REST/JSON:API endpoints. These tests will greatly assist in maintaining a robust testing framework for your headless Drupal applications.

The Role of Functional Testing in API Development

Functional testing is essential for verifying that your API performs its intended function. It checks the system's external behavior and ensures that the application behaves as expected after code changes. By running automated tests:

• Testing becomes quicker and less prone to human error.
• You can easily catch regressions, ensuring your APIs remain consistent as development progresses.
• Confidence is built across the development team that the system works as intended after deployments.

Setting Up Functional Tests in Drupal

Drupal provides a robust testing framework known as PHPUnit allowing you to create functional tests to simulate user actions and HTTP requests.

Step 1: Configure PHPUnit

First, ensure that PHPUnit is installed on your machine. You can check PHP and PHPUnit installation documentations if you're starting from scratch.

Step 2: Create a Functional Test Case

Navigate to the module where you want to implement your functional test. Inside the tests/src/Functional directory, create a PHP file for your test case:

cd modules/custom/your_module/tests/src/Functional
touch YourModuleTest.php

Within this file, set up your test class. This class should extend Drupal\Tests\BrowserTestBase, a helper class in Drupal for functional testing.

namespace Drupal\Tests\your_module\Functional;

use Drupal\Tests\BrowserTestBase;

/**
 * Tests for the your_module functionality.
 *
 * @group your_module
 */
class YourModuleTest extends BrowserTestBase {

  /**
   * Modules to enable.
   *
   * @var array
   */
  protected static $modules = ['your_module'];

  /**
   * Tests the your_module functionality.
   */
  public function testYourModuleFeature() {
    // Using drupalGet to check a specific API endpoint.
    $this->drupalGet('jsonapi/node/article');
    $this->assertSession()->statusCodeEquals(200);

    // Additional assertions can be added here.
  }
}
    

Step 3: Running Your Test

Run your test using the following command from your Drupal root directory:

./vendor/bin/phpunit --testsuite functional

This will execute your test cases, verifying that your JSON:API functionally responds correctly.

Best Practices for Functional Testing

• Maintain clear and descriptive test cases to ensure they are easy to understand for other team members.
• Use assertions generously to cover different aspects of your endpoints, from response codes to payload validations.
• Keep your tests modular; one test should not be dependent on the result of another test.

Conclusion and What’s Next?

Creating functional tests is an excellent way to ensure your API remains robust and reliable as you continue developing your Drupal application. By automating these tests, you'll save time and eliminate human error, leading to a healthier codebase.

In our next lesson, we will explore Validating GraphQL Responses with Tests. We'll dive into how you can extend your testing framework to cover GraphQL APIs, enriching your knowledge in headless Drupal applications. Stay tuned for more!