diff --git a/modules/simpletest/tests/cache.test b/modules/simpletest/tests/cache.test
index 1f3240d..664247b 100644
--- a/modules/simpletest/tests/cache.test
+++ b/modules/simpletest/tests/cache.test
@@ -152,14 +152,22 @@ class CacheSavingCase extends CacheTestCase {
     $this->assertTrue(isset($cached->data) && $cached->data == $test_object, t('Object is saved and restored properly.'));
   }
 
-  /*
+  /**
    * Check or a variable is stored and restored properly.
-   **/
+   */
   function checkVariable($var) {
     cache()->set('test_var', $var);
     $cached = cache()->get('test_var');
     $this->assertTrue(isset($cached->data) && $cached->data === $var, t('@type is saved and restored properly.', array('@type' => ucfirst(gettype($var)))));
   }
+
+  /**
+   * Test no empty cids are written in cache table.
+   */
+  function testNoEmptyCids() {
+    $this->drupalGet('user/register');
+    $this->assertFalse(cache_get(''), t('No cache entry is written with an empty cid.'));
+  }
 }
 
 /**