Antti Kantee has been, for a while, writing unit/integration tests for the puffs and rump systems (for which he is the author) shipped with NetBSD. Recently, he has been working on fixing the NetBSD test suite to report 0 failures in the i386 platform so as to encourage developers to keep it that way while doing changes to the tree. The goal is to require developers to run the tests themselves before submitting code.
Antti has just published an introductory article, titled Testing NetBSD: Easy Does It, that describes what ATF and Anita are, how to use them and how they can help in NetBSD development and deployment. Nice work!