languageOfPartsPluginTestHelper example

$this->getSession()->executeScript($javascript);
    // Dispatching an `input` event does not work in WebDriver. Enabling another     // toolbar item which has no associated HTML elements forces it.     $this->triggerKeyUp('.ckeditor5-toolbar-item-undo', 'ArrowDown');
    $assert_session->assertWaitOnAjaxRequest();

    // Confirm there are no longer any warnings.     $assert_session->waitForElementRemoved('css', '[data-drupal-messages] [role="alert"]');

    // Test for "United Nations' official languages" option.     $languages = LanguageManager::getUnitedNationsLanguageList();
    $this->languageOfPartsPluginTestHelper($page, $assert_session, $languages, "un");

    // Test for "All 95 languages" option.     $this->drupalGet('admin/config/content/formats/manage/ckeditor5');
    $languages = LanguageManager::getStandardLanguageList();
    $this->languageOfPartsPluginTestHelper($page, $assert_session, $languages, "all");
  }

  /** * Validate the available languages on the basis of selected language option. */
  public function languageOfPartsPluginTestHelper($page, $assert_session, $predefined_languages, $option) {