Starting with an app already in development, I have carried out the instructions in the iPhone Development Guide – Unit Testing Applications

I can successfully include and use my App's classes in Application-style tests that run on the device, and output their results to the console.

If I add the following line of code:

STAssertTrue([viewController isKindOfClass:[LoginViewController class]], @"Top view controller is not LoginViewController");

The following build error is generated:

Undefined symbols:
  "_OBJC_CLASS_$_LoginViewController", referenced from:
      __objc_classrefs__DATA@0 in LoginViewTest.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

I can provide more configuration information for the project and the Testing target, but the setup works file without the [LoginViewController class] line in the test source.

Without that line, I can reference the class, use it's properties and send it messages successfully.

Is there a linking build setting, or bundle loading option that is required when attempting to use an App class in this fashion? Or should I find another type of test to confirm that the class of an object is the expected one?