diff --git a/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php
index 1eec831..2fa841c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php
@@ -21,6 +21,13 @@
    */
   protected $storageClass;
 
+  /**
+   * An array of random stdClass objects.
+   *
+   * @var array
+   */
+  protected $objects = array();
+
   protected function setUp() {
     parent::setUp();
 
@@ -29,6 +36,11 @@ protected function setUp() {
 
     $this->store1 = new $this->storageClass($this->collection1);
     $this->store2 = new $this->storageClass($this->collection2);
+
+    // Create several objects for testing.
+    for ($i = 0; $i <= 5; $i++) {
+      $this->objects[$i] = $this->randomObject();
+    }
   }
 
   /**
@@ -40,49 +52,51 @@ public function testCRUD() {
     $this->assertIdentical($this->store2->getCollectionName(), $this->collection2);
 
     // Verify that an item can be stored.
-    $this->store1->set('foo', 'bar');
-    $this->assertIdentical('bar', $this->store1->get('foo'));
+    $this->store1->set('foo', $this->objects[0]);
+    $this->assertIdenticalObject($this->objects[0], $this->store1->get('foo'));
     // Verify that the other collection is not affected.
     $this->assertFalse($this->store2->get('foo'));
 
     // Verify that an item can be updated.
-    $this->store1->set('foo', 'baz');
-    $this->assertIdentical('baz', $this->store1->get('foo'));
+    $this->store1->set('foo', $this->objects[1]);
+    $this->assertIdenticalObject($this->objects[1], $this->store1->get('foo'));
     // Verify that the other collection is still not affected.
     $this->assertFalse($this->store2->get('foo'));
 
     // Verify that a collection/name pair is unique.
-    $this->store2->set('foo', 'other');
-    $this->assertIdentical('baz', $this->store1->get('foo'));
-    $this->assertIdentical('other', $this->store2->get('foo'));
+    $this->store2->set('foo', $this->objects[2]);
+    $this->assertIdenticalObject($this->objects[1], $this->store1->get('foo'));
+    $this->assertIdenticalObject($this->objects[2], $this->store2->get('foo'));
 
     // Verify that an item can be deleted.
     $this->store1->delete('foo');
     $this->assertFalse($this->store1->get('foo'));
 
     // Verify that the other collection is not affected.
-    $this->assertIdentical('other', $this->store2->get('foo'));
+    $this->assertIdenticalObject($this->objects[2], $this->store2->get('foo'));
     $this->store2->delete('foo');
     $this->assertFalse($this->store2->get('foo'));
 
     // Verify that multiple items can be stored.
     $values = array(
-      'foo' => 'bar',
-      'baz' => 'qux',
+      'foo' => $this->objects[3],
+      'bar' => $this->objects[4],
     );
     $this->store1->setMultiple($values);
 
     // Verify that multiple items can be retrieved.
-    $result = $this->store1->getMultiple(array('foo', 'baz'));
-    $this->assertIdentical($values, $result);
+    $result = $this->store1->getMultiple(array('foo', 'bar'));
+    foreach ($values as $j => $value) {
+      $this->assertIdenticalObject($value, $result[$j]);
+    }
 
     // Verify that the other collection was not affected.
     $this->assertFalse($this->store2->get('foo'));
-    $this->assertFalse($this->store2->get('baz'));
+    $this->assertFalse($this->store2->get('bar'));
 
     // Verify that all items in a collection can be retrieved.
     // Ensure that an item with the same name exists in the other collection.
-    $this->store2->set('foo', 'other');
+    $this->store2->set('foo', $this->objects[5]);
     $result = $this->store1->getAll();
     // Not using assertIdentical(), since the order is not defined for getAll().
     $this->assertEqual(count($result), count($values));
@@ -91,15 +105,15 @@ public function testCRUD() {
     }
     // Verify that all items in the other collection are different.
     $result = $this->store2->getAll();
-    $this->assertEqual($result, array('foo' => 'other'));
+    $this->assertEqual($result, array('foo' => $this->objects[5]));
 
     // Verify that multiple items can be deleted.
     $this->store1->deleteMultiple(array_keys($values));
     $this->assertFalse($this->store1->get('foo'));
     $this->assertFalse($this->store1->get('bar'));
-    $this->assertFalse($this->store1->getMultiple(array('foo', 'baz')));
+    $this->assertFalse($this->store1->getMultiple(array('foo', 'bar')));
     // Verify that the item in the other collection still exists.
-    $this->assertIdentical('other', $this->store2->get('foo'));
+    $this->assertIdenticalObject($this->objects[5], $this->store2->get('foo'));
   }
 
   /**
@@ -123,4 +137,30 @@ public function testNonExistingKeys() {
     $this->assertFalse(isset($values['foo']), "Key 'foo' not found.");
     $this->assertIdentical($values['bar'], 'baz');
   }
+
+  /**
+   * Tests the setIfNotExists() method.
+   */
+  public function testSetIfNotExists() {
+
+    $key = $this->randomName();
+    // Test that setIfNotExists() succeeds only the first time.
+    for ($i = 0; $i <= 1; $i++) {
+      // setIfNotExists() should fail the second time ($i = 1).
+      $this->assertEqual(!$i, $this->store1->setIfNotExists($key, $this->objects[$i]));
+      $this->assertIdenticalObject($this->objects[0], $this->store1->get($key));
+      // Verify that the other collection is not affected.
+      $this->assertFalse($this->store2->get($key));
+    }
+
+    // Remove the item and try to set it again.
+    $this->store1->delete($key);
+    $this->store1->setIfNotExists($key, $this->objects[1]);
+    // This time it should succeed.
+    $this->assertIdenticalObject($this->objects[1], $this->store1->get($key));
+    // Verify that the other collection is still not affected.
+    $this->assertFalse($this->store2->get($key));
+
+  }
+
 }