Comprehensive Unit Tests

Someone at work sent this article to me.  It makes a lot of sense, so I'm recommending it here.
http://www.infoq.com/articles/Comprehensive-Unit-Test

And of course, I can't resist the urge to add my own two cents.

• A good mock object library can make your life a ton easier.  Make sure to take time to look around at what options are out there.
• Always make it clear what question the unit test is asking.  If I can't tell when a test is no longer applicable from its name or some introductory text, then it's got a problem.