GH-Unit for unit testing Objective-C code, why am I getting linking errors?

Question

I\'m trying to dive into the quite frankly terrible world of unit testing using Xcode (such a convoluted process it seems.)

Basically I have this test class, attempt

Answer 1

Somehow Apple's example works without duplicating the .m files in the target.

Download Apple's unit testing sample code (iPhoneUnitTests.zip) here:

http://developer.apple.com/IPhone/library/samplecode/iPhoneUnitTests/Introduction/Intro.html

Click on the CalcTests target. Only CalcTests.m is in this target.

Build the target. It builds without any link errors for CalcAppDelegate or other classes.

What's the magic that makes this work?