Unittesting Biztalk map that read value from SSO

I have a Biztalk 2013 R2 (x64) installed. I have created a BTS map which read some user credential from SSO. I created a unittest for testing this map but getting this error:

"An exeception of type 'Microsoft.BizTalk.TestTools.BizTalkTestAssertFailException' occurred in Microsoft.BizTalk.TestTools.dll but was not handled in user code.

Additional information: Transformation Failure.

It seems like that my map doesn't have access to read from the SSO. I'm running the test from VS2013, so the user will be me. How can I change or run the test with different user? I tried to create a Test.Setting file even this didn't help..

Thanks in advance..