--- /dev/null
+<?php
+
+/**
+ * @file
+ * Helper module for the html mail and url conversion tests.
+ */
+
+/**
+ * Implements hook_mail().
+ */
+function mail_html_test_mail($key, &$message, $params) {
+ switch ($key) {
+ case 'render_from_message_param':
+ $message['body'][] = \Drupal::service('renderer')->renderPlain($params['message']);
+ break;
+ }
+}