ActionsTest.php

<?php

namespace Drupal\KernelTests\Core\Render\Element;

use Drupal\Core\Form\FormInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\KernelTests\KernelTestBase;

/**
 * @coversDefaultClass \Drupal\Core\Render\Element\Actions
 * @group Render
 */
class ActionsTest extends KernelTestBase implements FormInterface {
    
    /**
     * {@inheritdoc}
     */
    protected static $modules = [
        'system',
    ];
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return __CLASS__;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['key'] = [
            '#type' => 'submit',
            '#value' => 'Key',
            '#dropbutton' => 'submit',
            '#cache' => [
                'tags' => [
                    'foo',
                ],
            ],
            '#attached' => [
                'library' => [
                    'system/base',
                ],
            ],
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => 'Save',
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
    }
    public function testDropbuttonWithBubbleableMetadata() {
        $result = \Drupal::formBuilder()->getForm($this);
        \Drupal::service('renderer')->renderRoot($result);
        $this->assertEquals([
            'system/base',
            'core/drupal.dropbutton',
        ], $result['#attached']['library']);
        $this->assertEquals([
            'foo',
        ], $result['#cache']['tags']);
    }

}