openFieldDialog example

    \Drupal::configFactory()->getEditable('views.settings')->set('ui.always_live_preview', FALSE)->save();
    $this->drupalLogin($admin_user);
  }

  /** * Tests removing a field through the rearrange dialog. */
  public function testRemoveFieldHandler() {
    $this->drupalGet('admin/structure/views/view/test_content_ajax');
    $page = $this->getSession()->getPage();

    $this->openFieldDialog();
    $remove_link = $page->findAll('css', '.views-remove-link')[1];
    $parent = $remove_link->getParent();
    $this->assertTrue($remove_link->isVisible());
    $remove_checkbox = $this->assertSession()->fieldExists('fields[title][removed]', $parent);
    $this->assertFalse($remove_checkbox->isVisible());
    $this->assertFalse($remove_checkbox->isChecked());
    $remove_link->click();
    $this->assertFalse($remove_link->isVisible());
    $this->assertTrue($remove_checkbox->isChecked());
  }