diff --git a/core/lib/Drupal/Core/Render/theme.api.php b/core/lib/Drupal/Core/Render/theme.api.php
index 3b92f2a8f9..642555cbcc 100644
--- a/core/lib/Drupal/Core/Render/theme.api.php
+++ b/core/lib/Drupal/Core/Render/theme.api.php
@@ -651,7 +651,7 @@ function hook_preprocess_HOOK(&$variables) {
  * @see hook_theme_suggestions_HOOK_alter()
  */
 function hook_theme_suggestions_HOOK(array $variables) {
-  $suggestions = array();
+  $suggestions = [];
   // If the node language is French, this would provide node--fr.html.twig as an
   // optional template override for French nodes.
   $suggestions[] = 'node__' . $variables['elements']['#langcode'];
diff --git a/core/modules/system/tests/modules/theme_test/theme_test.module b/core/modules/system/tests/modules/theme_test/theme_test.module
index 57a2a157d0..ddcb29a58a 100644
--- a/core/modules/system/tests/modules/theme_test/theme_test.module
+++ b/core/modules/system/tests/modules/theme_test/theme_test.module
@@ -21,27 +21,27 @@ function theme_test_theme($existing, $type, $theme, $path) {
   ];
   $items['theme_test_template_test_2'] = [
     'template' => 'theme_test.template_test',
-  );
-  $items['theme_test_suggestion_provided'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_specific_suggestions'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_suggestions'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_general_suggestions'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_array_suggestions'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_array_suggestions_without_base'] = array(
-    'variables' => array(),
-  );
-  $items['theme_test_function_suggestions'] = array(
-    'variables' => array(),
+  ];
+  $items['theme_test_suggestion_provided'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_specific_suggestions'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_suggestions'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_general_suggestions'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_array_suggestions'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_array_suggestions_without_base'] = [
+    'variables' => [],
+  ];
+  $items['theme_test_function_suggestions'] = [
+    'variables' => [],
     'function' => 'theme_theme_test_function_suggestions',
   ];
   $items['theme_test_suggestions_include'] = [