class DisplayTest

1. 9.x drupal/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayTest.php \Drupal\views\Tests\Plugin\DisplayTest
2. 9.x drupal/core/modules/views/lib/Drupal/views/Tests/UI/DisplayTest.php \Drupal\views\Tests\UI\DisplayTest
3. 9.x drupal/core/modules/views/tests/views_test_data/lib/Drupal/views_test_data/Plugin/views/display/DisplayTest.php \Drupal\views_test_data\Plugin\views\display\DisplayTest

DisplayTest.php in drupal/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayTest.php

Definition of Drupal\views\Tests\Plugin\DisplayTest.

class DisplayTest extends DisplayPluginBase {

  /**
   * Whether the display allows attachments.
   *
   * @var bool
   */
  protected $usesAttachments = TRUE;

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::defineOptions().
   */
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['test_option'] = array(
      'default' => '',
    );
    return $options;
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::optionsSummaryv().
   */
  public function optionsSummary(&$categories, &$options) {
    parent::optionsSummary($categories, $options);
    $categories['display_test'] = array(
      'title' => t('Display test settings'),
      'column' => 'second',
      'build' => array(
        '#weight' => -100,
      ),
    );
    $test_option = $this
      ->getOption('test_option') ?: t('Empty');
    $options['test_option'] = array(
      'category' => 'display_test',
      'title' => t('Test option'),
      'value' => views_ui_truncate($test_option, 24),
    );
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::buildOptionsForm().
   */
  public function buildOptionsForm(&$form, &$form_state) {
    parent::buildOptionsForm($form, $form_state);
    switch ($form_state['section']) {
      case 'test_option':
        $form['#title'] .= t('Test option');
        $form['test_option'] = array(
          '#type' => 'textfield',
          '#description' => t('This is a textfield for test_option.'),
          '#default_value' => $this
            ->getOption('test_option'),
        );
        break;
    }
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::validateOptionsForm().
   */
  public function validateOptionsForm(&$form, &$form_state) {
    parent::validateOptionsForm($form, $form_state);
    watchdog('views', $form_state['values']['test_option']);
    switch ($form_state['section']) {
      case 'test_option':
        if (!trim($form_state['values']['test_option'])) {
          form_error($form['test_option'], t('You cannot have an empty option.'));
        }
        break;
    }
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::submitOptionsForm().
   */
  public function submitOptionsForm(&$form, &$form_state) {
    parent::submitOptionsForm($form, $form_state);
    switch ($form_state['section']) {
      case 'test_option':
        $this
          ->setOption('test_option', $form_state['values']['test_option']);
        break;
    }
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::execute().
   */
  public function execute() {
    $this->view
      ->build();
    $render = $this->view
      ->render();

    // Render the test option as the title before the view output.
    $render['#prefix'] = '<h1>' . filter_xss_admin($this->options['test_option']) . '</h1>';
    return $render;
  }

  /**
   * Overrides Drupal\views\Plugin\views\display\DisplayPluginBase::preview().
   *
   * Override so preview and execute are the same output.
   */
  public function preview() {
    $element = $this
      ->execute();
    return drupal_render($element);
  }

}