class JSInteractionTestForm

class JSInteractionTestForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return __CLASS__;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        // No-op.
    }
    
    /**
     * Creates the test form.
     *
     * The form provides:
     * - A link that is obstructed (blocked) by another element.
     * - A link that, when clicked, removes the blocking element after some time.
     * - A field that is disabled.
     * - A link that, when clicked, enables the field after some time.
     *
     * @param array $form
     *   An associative array containing the structure of the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     *
     * @return array
     *   The form structure.
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        return [
            'target_link' => [
                '#type' => 'link',
                '#url' => Url::fromRoute('<current>'),
                '#title' => $this->t('Target link'),
            ],
            'blocker_element' => [
                '#type' => 'html_tag',
                '#tag' => 'div',
                '#attributes' => [
                    'class' => [
                        'blocker-element',
                    ],
                ],
            ],
            'remove_blocker_trigger' => [
                '#type' => 'link',
                '#url' => Url::fromRoute('<current>'),
                '#title' => $this->t('Remove Blocker Trigger'),
                '#attributes' => [
                    'class' => [
                        'remove-blocker-trigger',
                    ],
                ],
            ],
            'target_field' => [
                '#type' => 'textfield',
                '#maxlength' => 20,
                '#disabled' => TRUE,
            ],
            'enable_field_trigger' => [
                '#type' => 'link',
                '#url' => Url::fromRoute('<current>'),
                '#title' => $this->t('Enable Field Trigger'),
                '#attributes' => [
                    'class' => [
                        'enable-field-trigger',
                    ],
                ],
            ],
            '#attached' => [
                'library' => [
                    'js_interaction_test/js_interaction_test',
                ],
            ],
        ];
    }

}