Learning Test Case Basics by Writing a Hello World Test for Drupal 7

In this lesson we'll write a hello world test that navigates to the front page of a standard Drupal installation and verifies the existence of the text, "No front page content has been created yet.". This will allow us to walk through creating a .test file, adding it to our modules .info file, as well as cover the basics of extending DrupalWebTestCase to write our own test case. For this lesson we'll use the helloworld sample module as a starting point and expand it to add a very basic test. The goal being to gain a better understanding of how the SimpleTest module discovers, and runs our tests. Then in future lessons we can expand on our test case to add more robust features.

All SimpleTest tests are an extension of either the DrupalWebTestCase (we'll focus on this one), or the DrupalUnitTestCase base classes. There are two pieces to the discover process. Writing a new class that extends one of the base classes, and then declaring the file that contains this new class in your module's .info file so that the file and it's code are indexed and inserted into the registry.

Create a new file inside the helloworld module's directory: tests/helloworld.test. The convention is to name files that contain test classes with a .test extension. Similar to how module file, despite being purely PHP, are named with a .module extension.

Then we'll add a basic skeleton test class like so:

class HelloworldTests extends DrupalWebTestCase {
  /**
   * Metadata about our test case.
   */
  public static function getInfo() {
    return array(
      'name' => 'Hello World',
      'description' => 'Tests for the Hello World module.',
      'group' => 'Hello World Group',
    );
  }
}

Our class includes a getInfo() method, it's required, and it returns a simple associative array with meta-data about our test. This information is used by the SimpleTest UI and other test runners to provide human readable information about our tests and to do things like group like tests together. When you view the lists of tests in the SimpleTest UI, you're seeing the 'name', and 'description' provided by your test classes' getInfo() method.

All tests should have a setUp() method as well. This method is called by the test runner after Drupal has been installed, but before our tests are run. It gives us the chance to perform any additional configuration on the environment within which the tests are running. In our case, we need to enable the helloworld module since it's not part of the default install profile. We can do that by delegating to the parent classes' setUp() method and passing an array of modules we want enabled. That might look something like this:

/**
 * Perform any setup tasks for our test case.
 */
public function setUp() {
  parent::setUp(array('helloworld'));
}

Finally, we need to provide at least one method whose name starts with "test". This method, and all others whose name starts with test will be called in succession by the test runner and are expected to contain the assertions that make up our individual test.

public function testHelloWorld() {
  $this->drupalGet('helloworld');
  $this->assertText('Hello World. Welcome to Drupal.', 'The page content is present.');
}

This test will navigate to the url /helloworld, and then verify that the text "Hello World. Welcome to Drupal.", is displayed on the page.

In order for our test to show up in the SimpleTest UI we need to add it to the registry. We can do so by modifying the helloworld.info file and adding the line files[] = tests/helloworld.test to the file. Then clear the cache and Drupal should discover your new test case and allow you to run the tests either through the SimpleTest UI or with drush.

Additional resources

DrupalWebTestCase documentation
Written tutorial based on this video