A few notes here: I don’t use Unit Tests as much as I should (probably true of most of us, I guess). I had built a good, functioning example for a Cocoa class a year or two back, and wanted to make use of that in a new project.
There’s a reasonable guide on the ADC site, at ADC—Automated Unit Testing with Xcode 3 and Objective-C. There’s also a lot of out dated guides, which sort of get in the way.
I hit a problem with my build:
"<SenTestingKit/SenTestingKit.h> no such file". After a certain amount of thrashing around, finding several mailing list posts from people with the same problem, and no help from careful reading of the ADC guide, I found the solution: make sure that your test classes are in the Unit Tests target, and not the main project target (look at the check boxes under each target).
Another useful link is: Chris Hanson’s Xcode unit testing articles updated.