When I run unit tests in Xcode GUI I receive this warning
Skipping tests; the iPhoneSimulator platform does not currently support application-hosted tests (TEST_HOST set).

Xcode doesn’t execute my unit tests but I get the message that Test Succeeded. It looks like it just skips my test.
P.S. I know lot of people get this error when running Unit test from the Command Line but this happens in Xcode GUI
Xcode cannot run application hosted Unit Tests.
There are workarounds for it from the developer site: http://developer.apple.com/library/ios/#documentation/developertools/Conceptual/UnitTesting/02-Setting_Up_Unit_Tests_in_a_Project/setting_up.html