commit 5f8c06bd11e8fdf12415267e3639606c2d9d841c
Author: fago <nuppla@zites.net>
Date:   Sun Jun 30 14:36:08 2013 +0200

    Stringinterface test fix.

diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
index 343f33a..c459784 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
@@ -12,6 +12,7 @@
 use Drupal\Core\Entity\Field\FieldItemInterface;
 use Drupal\Core\Language\Language;
 use Drupal\Core\TypedData\Type\String;
+use Drupal\Core\TypedData\Type\StringInterface;
 use Drupal\Core\TypedData\TypedDataInterface;
 
 /**
@@ -508,8 +509,7 @@ protected function assertDataStructureInterfaces($entity_type) {
    */
   public function getContainedStrings(TypedDataInterface $wrapper, $depth, array &$strings) {
 
-    // @todo Switch to check StringInterface as soon as it is in place.
-    if ($wrapper instanceof String) {
+    if ($wrapper instanceof StringInterface) {
       $strings[] = $wrapper->getValue();
     }