diff --git a/tests/unit/DbTest.php b/tests/unit/DbTest.php
index <HASH>..<HASH> 100644
--- a/tests/unit/DbTest.php
+++ b/tests/unit/DbTest.php
@@ -1716,5 +1716,19 @@ class DbTest extends TestCase
 

         $this->assertNotNull($member['id']);

     }

+

+    public function testNullAsCollectionKey()

+    {

+        $this->initFixtures();

+

+        $members = $this->db('member');

+

+        $members[] = $this->db('member');

+        $members[] = $this->db('member');

+        $members[] = $this->db('member');

+        $members[] = $this->db('member');

+

+        $this->assertEquals(4, $members->length());

+    }

 }
added test for null as collection key