class ClaroVerticalTabsTest

class ClaroVerticalTabsTest extends KernelTestBase {
  
  /**
   * {@inheritdoc}
   */
  protected static $modules = [
    'system',
  ];
  
  /**
   * Confirms that Claro can render vertical tabs correctly.
   */
  public function testVerticalTabs() {
    // Enable the Claro theme.
    \Drupal::service('theme_installer')->install([
      'claro',
    ]);
    $this->config('system.theme')
      ->set('default', 'claro')
      ->save();
    $form = [
      '#parents' => [
        'parent',
      ],
      '#array_parents' => [],
      '#tree' => TRUE,
    ];
    $form['vertical_tabs'] = [
      '#type' => 'vertical_tabs',
      '#title' => 'Vertical Tabs',
    ];
    $form['vertical_tabs_details'] = [
      '#type' => 'details',
      '#title' => 'Details',
      '#group' => 'parent][vertical_tabs',
    ];
    // Needs to be rendered after the vertical tabs.
    $form['container'] = [
      '#type' => 'container',
      '#title' => 'Container',
    ];
    $form['container_details'] = [
      '#type' => 'details',
      '#title' => 'Details',
      '#group' => 'container',
    ];
    /** @var \Drupal\Core\Form\FormBuilderInterface $form_builder */
    $form_builder = $this->container
      ->get('form_builder');
    $form_state = new FormState();
    $form_builder->doBuildForm('form', $form, $form_state);
    $this->render($form);
    // Assert that the vertical tab details has the appropriate class.
    $this->assertCount(1, $this->cssSelect('.vertical-tabs__items details.vertical-tabs__item'));
    // Assert that there is a details element.
    $this->assertCount(1, $this->cssSelect('#edit-parent-container-details'));
    // Assert that details element doesn't have the vertical tab classes.
    $this->assertCount(0, $this->cssSelect('#edit-parent-container-details.vertical-tabs__item'));
  }

}