diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldInfoTest.php b/core/modules/field/lib/Drupal/field/Tests/FieldInfoTest.php
index 3115851..bbf90a2 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldInfoTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldInfoTest.php
@@ -304,7 +304,6 @@ function testFieldMap() {
     $this->assertEqual($map, $expected);
   }
 
-
   /**
    * Test that the field_info settings convenience functions work.
    */
@@ -329,6 +328,31 @@ function testSettingsInfo() {
       $this->assertIdentical(field_info_formatter_settings($type), $info['settings'], format_string("field_info_formatter_settings returns %type's formatter settings", array('%type' => $type)));
     }
   }
+  
+  /**
+   * Tests that the field info cache can be built correctly.
+   */
+  function testFieldInfoCache() {
+    // Create a test field and ensure it's in the array returned by
+    // field_info_fields().
+    $field_name = drupal_strtolower($this->randomName());
+    $field = array(
+      'field_name' => $field_name,
+      'type' => 'test_field',
+    );
+    field_create_field($field);
+    $fields = field_info_fields();
+    $this->assertTrue(isset($fields[$field_name]), 'The test field is initially found in the array returned by field_info_fields().');
+    
+    // Now rebuild the field info cache, and set a variable which will cause
+    // the cache to be cleared while it's being rebuilt; see
+    // field_test_entity_info(). Ensure the test field is still in the returned
+    // array.
+    field_info_cache_clear();
+    variable_set('field_test_clear_info_cache_in_hook_entity_info', TRUE);
+    $fields = field_info_fields();
+    $this->assertTrue(isset($fields[$field_name]), 'The test field is found in the array returned by field_info_fields() even if its cache is cleared while being rebuilt.');
+  }
 
   /**
    * Test that the widget definition functions work.
diff --git a/core/modules/field/tests/modules/field_test/field_test.entity.inc b/core/modules/field/tests/modules/field_test/field_test.entity.inc
index 81c116d..4536078 100644
--- a/core/modules/field/tests/modules/field_test/field_test.entity.inc
+++ b/core/modules/field/tests/modules/field_test/field_test.entity.inc
@@ -9,6 +9,17 @@
 use Drupal\field_test\Plugin\Core\Entity\TestEntity;
 
 /**
+ * Implements hook_entity_info().
+ */
+function field_test_entity_info() {
+  // If requested, clear the field cache while this is being called. See
+  // testFieldInfoCache().
+  if (variable_get('field_test_clear_info_cache_in_hook_entity_info', FALSE)) {
+    field_info_cache_clear();
+  }
+}
+
+/**
  * Implements hook_entity_info_alter().
  */
 function field_test_entity_info_alter(&$entity_info) {
-- 
1.7.10.2 (Apple Git-33)