diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index 760947f..d88b528 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -84,10 +84,12 @@ function simpletest_theme() {
     'simpletest_test_table' => array(
       'render element' => 'table',
       'file' => 'simpletest.pages.inc',
+      'template' => 'simpletest-test-table',
     ),
     'simpletest_result_summary' => array(
-      'render element' => 'form',
+      'variables' => array('form' => NULL),
       'file' => 'simpletest.pages.inc',
+      'template' => 'simpletest-result-summary',
     ),
   );
 }
diff --git a/core/modules/simpletest/simpletest.pages.inc b/core/modules/simpletest/simpletest.pages.inc
index 7fe64d7..fc7e649 100644
--- a/core/modules/simpletest/simpletest.pages.inc
+++ b/core/modules/simpletest/simpletest.pages.inc
@@ -63,7 +63,7 @@ function simpletest_test_form($form) {
  *
  * @ingroup themeable
  */
-function theme_simpletest_test_table($variables) {
+function template_preprocess_simpletest_test_table($variables) {
   $table = $variables['table'];
 
   drupal_add_library('simpletest', 'drupal.simpletest');
@@ -166,10 +166,10 @@ function theme_simpletest_test_table($variables) {
   drupal_add_js(array('simpleTest' => $js), 'setting');
 
   if (empty($rows)) {
-    return '<strong>' . t('No tests to display.') . '</strong>';
+    $variables['table'] = '<strong>' . t('No tests to display.') . '</strong>';
   }
   else {
-    return theme('table', array('header' => $header, 'rows' => $rows, 'attributes' => array('id' => 'simpletest-form-table')));
+    $variables['table'] = theme('table', array('header' => $header, 'rows' => $rows, 'attributes' => array('id' => 'simpletest-form-table')));
   }
 }
 
@@ -371,9 +371,10 @@ function simpletest_result_form_submit($form, &$form_state) {
  *
  * @ingroup themeable
  */
-function theme_simpletest_result_summary($variables) {
+function template_preprocess_simpletest_result_summary($variables) {
   $form = $variables['form'];
-  return '<div class="simpletest-' . ($form['#ok'] ? 'pass' : 'fail') . '">' . _simpletest_format_summary_line($form) . '</div>';
+  $variables['summary'] = _simpletest_format_summary_line($form);
+  $variables['status'] = $form['#ok'] ? 'pass' : 'fail';
 }
 
 /**
diff --git a/core/modules/simpletest/templates/simpletest-result-summary.html.twig b/core/modules/simpletest/templates/simpletest-result-summary.html.twig
new file mode 100644
index 0000000..c8538c1
--- /dev/null
+++ b/core/modules/simpletest/templates/simpletest-result-summary.html.twig
@@ -0,0 +1,16 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the content of simpletest result summary
+ *
+ * Available variables:
+ * - status: Pass or fail of test
+ * - summary: Summary info of test
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_admin_block_content()
+ *
+ * @ingroup themeable
+ */
+#}
+<div class="simpletest-{{ status }}>{{ summary }}</div>
diff --git a/core/modules/simpletest/templates/simpletest-test-table.html.twig b/core/modules/simpletest/templates/simpletest-test-table.html.twig
new file mode 100644
index 0000000..c51180c
--- /dev/null
+++ b/core/modules/simpletest/templates/simpletest-test-table.html.twig
@@ -0,0 +1,15 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the content of simpletest result summary
+ *
+ * Available variables:
+ * - table: A simpletest table
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_admin_block_content()
+ *
+ * @ingroup themeable
+ */
+#}
+{{ $table }}