I stumbled upon the latest version of the official tutorial for ‘writing Unit Tests for SharePoint using Behaviors, Moles and Pex’. It’s certainly worth reading! If you don’t know what Pex or ‘White Box Unit Testing’ is, you should go have a look at the official site (Pex can also be used to do white box unit testing on non-SharePoint applications).
For those interested in this topic, ‘Testing SharePoint with Pex’ is also one of the sessions on the Belgian Community Day 2010, given by my colleague Tom Van Gaever.