--- /dev/null
+<?php
+
+namespace Drupal\js_ajax_test\Form;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\js_ajax_test\Ajax\JsAjaxTestCommand;
+
+/**
+ * Test form for js_ajax_test
+ *
+ * @internal
+ */
+class JsAjaxTestForm extends FormBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getFormId() {
+ return 'js_ajax_test_form';
+ }
+
+ /**
+ * Form for testing the addition of various types of elements via Ajax.
+ */
+ public function buildForm(array $form, FormStateInterface $form_state) {
+ $form['#attached']['library'][] = 'js_ajax_test/ajax';
+ $form['custom']['#prefix'] = '<div id="js_ajax_test_form_wrapper">';
+ $form['custom']['#suffix'] = '</div>';
+
+ // Button to test for the waitForButton() assertion.
+ $form['test_button'] = [
+ '#type' => 'submit',
+ '#value' => $this->t('Add button'),
+ '#button_type' => 'primary',
+ '#ajax' => [
+ 'callback' => [static::class, 'addButton'],
+ 'progress' => [
+ 'type' => 'throbber',
+ 'message' => NULL,
+ ],
+ 'wrapper' => 'js_ajax_test_form_wrapper',
+ ],
+ ];
+ return $form;
+ }
+
+ /**
+ * Ajax callback for the "Add button" button.
+ */
+ public static function addButton(array $form, FormStateInterface $form_state) {
+ return (new AjaxResponse())
+ ->addCommand(new JsAjaxTestCommand());
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function submitForm(array &$form, FormStateInterface $form_state) {
+ // An empty implementation, as we never submit the actual form.
+ }
+
+}