class ServiceProviderWebTest

class ServiceProviderWebTest extends BrowserTestBase {
  
  /**
   * Modules to enable.
   *
   * @var array
   */
  protected static $modules = [
    'file',
    'service_provider_test',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * Tests that module service providers get registered to the DIC.
   *
   * Also tests that services provided by module service providers get
   * registered to the DIC.
   */
  public function testServiceProviderRegistrationIntegration() {
    $this->assertTrue(\Drupal::hasService('service_provider_test_class'), 'The service_provider_test_class service has been registered to the DIC');
    // The event subscriber method in the test class calls
    // \Drupal\Core\Messenger\MessengerInterface::addStatus() with a message
    // saying it has fired. This will fire on every page request so it should
    // show up on the front page.
    $this->drupalGet('');
    $this->assertSession()
      ->pageTextContains('The service_provider_test event subscriber fired!');
  }

}