diff --git a/core/modules/system/tests/src/Functional/Form/FormTest.php b/core/modules/system/tests/src/Functional/Form/FormTest.php
index 3731f06..7df29f3 100644
--- a/core/modules/system/tests/src/Functional/Form/FormTest.php
+++ b/core/modules/system/tests/src/Functional/Form/FormTest.php
@@ -469,7 +469,6 @@ public function testEmptySelect() {
    */
   public function testSelectSorting() {
     $this->drupalGet('form-test/select');
-    $content = $this->getSession()->getPage()->getContent();
 
     // Verify the order of the select options.
     $this->validateSelectSorting('unsorted', [
@@ -549,17 +548,17 @@ public function testSelectSorting() {
    * @param string[] $order
    *   Expected order of its options.
    */
-  protected function validateSelectSorting($select, $order) {
-    $option_map_function = function (NodeElement $option) {
-      if ($option->getTagName() === 'optgroup') {
-        return $option->getAttribute('label');
-      }
-      return $option->getValue();
+  protected function validateSelectSorting($select, array $order) {
+    $option_map_function = function (NodeElement $node) {
+      return ($node->getTagName() === 'optgroup') ?
+        $node->getAttribute('label') : $node->getValue();
     };
+    $option_nodes = $this->getSession()
+      ->getPage()
+      ->findField($select)
+      ->findAll('css', 'option, optgroup');
 
-    $field = $this->getSession()->getPage()->findField($select);
-    $options = array_map($option_map_function,
-      $field->findAll('css', 'option, optgroup'));
+    $options = array_map($option_map_function, $option_nodes);
     $this->assertIdentical($order, $options);
   }