diff --git a/core/modules/system/src/Tests/Form/ElementsFieldsetTest.php b/core/modules/system/src/Tests/Form/ElementsFieldsetTest.php
index 111d895..82b3d79 100644
--- a/core/modules/system/src/Tests/Form/ElementsFieldsetTest.php
+++ b/core/modules/system/src/Tests/Form/ElementsFieldsetTest.php
@@ -21,7 +21,7 @@ class ElementsFieldsetTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('form_test');
+  public static $modules = ['form_test'];
 
   /**
    * Tests different display options for fieldset element descriptions.
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestGroupFieldsetForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestGroupFieldsetForm.php
index 123756d..58d6136 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestGroupFieldsetForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestGroupFieldsetForm.php
@@ -26,67 +26,67 @@ public function getFormId() {
    * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
-    $form['fieldset'] = array(
+    $form['fieldset'] = [
       '#type' => 'fieldset',
       '#title' => 'Fieldset',
-    );
-    $form['meta'] = array(
+    ];
+    $form['meta'] = [
       '#type' => 'container',
       '#title' => 'Group element',
       '#group' => 'fieldset',
-    );
-    $form['meta']['element'] = array(
+    ];
+    $form['meta']['element'] = [
       '#type' => 'textfield',
       '#title' => 'Nest in container element',
-    );
+    ];
 
-    $form['fieldset_before'] = array(
+    $form['fieldset_before'] = [
       '#type' => 'fieldset',
       '#title' => 'Fieldset test for description before element',
       '#description' => 'Fieldset test for description before element.',
       '#description_display' => 'before',
-    );
-    $form['meta_before'] = array(
+    ];
+    $form['meta_before'] = [
       '#type' => 'container',
       '#title' => 'Group element',
       '#group' => 'fieldset_before',
-    );
-    $form['meta_before']['element'] = array(
+    ];
+    $form['meta_before']['element'] = [
       '#type' => 'textfield',
       '#title' => 'Nest in container element',
-    );
+    ];
 
-    $form['fieldset_after'] = array(
+    $form['fieldset_after'] = [
       '#type' => 'fieldset',
       '#title' => 'Fieldset test for description after element',
       '#description' => 'Fieldset test for description after element.',
       '#description_display' => 'after',
-    );
-    $form['meta_after'] = array(
+    ];
+    $form['meta_after'] = [
       '#type' => 'container',
       '#title' => 'Group element',
       '#group' => 'fieldset_after',
-    );
-    $form['meta_after']['element'] = array(
+    ];
+    $form['meta_after']['element'] = [
       '#type' => 'textfield',
       '#title' => 'Nest in container element',
-    );
+    ];
 
-    $form['fieldset_invisible'] = array(
+    $form['fieldset_invisible'] = [
       '#type' => 'fieldset',
       '#title' => 'Fieldset test for visually-hidden description',
       '#description' => 'Fieldset test for visually-hidden description.',
       '#description_display' => 'invisible',
-    );
-    $form['meta_invisible'] = array(
+    ];
+    $form['meta_invisible'] = [
       '#type' => 'container',
       '#title' => 'Group element',
       '#group' => 'fieldset_invisible',
-    );
-    $form['meta_invisible']['element'] = array(
+    ];
+    $form['meta_invisible']['element'] = [
       '#type' => 'textfield',
       '#title' => 'Nest in container element',
-    );
+    ];
     return $form;
   }