diff --git a/core/tests/Drupal/Tests/Core/Template/AttributeTest.php b/core/tests/Drupal/Tests/Core/Template/AttributeTest.php
index 9f2cb50..a5cad7b 100644
--- a/core/tests/Drupal/Tests/Core/Template/AttributeTest.php
+++ b/core/tests/Drupal/Tests/Core/Template/AttributeTest.php
@@ -69,6 +69,25 @@ public function testAddClasses() {
     $attribute->addClass();
     $this->assertEmpty($attribute['class']);
 
+    // Test various permutations of adding values to empty Attribute objects.
+    foreach (array(NULL, FALSE, '', []) as $value) {
+      // Single value.
+      $attribute->addClass($value);
+      $this->assertEmpty($attribute['class']);
+
+      // Multiple values.
+      $attribute->addClass($value, $value);
+      $this->assertEmpty($attribute['class']);
+
+      // Single value in array.
+      $attribute->addClass([$value]);
+      $this->assertEmpty($attribute['class']);
+
+      // Single value in arrays.
+      $attribute->addClass([$value], [$value]);
+      $this->assertEmpty($attribute['class']);
+    }
+
     // Add one class on empty attribute.
     $attribute->addClass('banana');
     $this->assertArrayEquals(array('banana'), $attribute['class']->value());