Running OCUnit test case in Simulator

Hello. I am writing OCUnit tests for an existing project.

It's going ok, but I have become stuck running a test which uses NSURLConnection to test server communication.
The runtime environment is just not firing the NSURLConnection at all (delegate methods are never called).

I think this is because the tests are not running in an iOS context on Simulator (tests run but Simulator is not invoked). I think I need to edit the 'Test Host' for the Project Test Target to get it to run the test for Simulator instead, but it's not clear what is the expected value for 'Test Host' should be, in project settings:

Can anyone advise?  How can I get my NSURLConnection reliant test to run?  The ASynchronicity is not a problem; I have NSCondition locks to handle this, the NSURLConnection just never starts.

Thanks.