I really like that. I've seen code so full of trivial unit tests, yet no integration or regression testing.
A good unit test should be written with the mindset of a hacker - how can I break it - rather than just a few assertions. It's not easy to do, and that's why there's so much bad stuff.
In my experience the best tests have the structure of a specification. Some flavor of test-first discipline is the easiest way I know of to achieve this. This way when requirements change, you change the tests such that they match the new specification. Sometimes this reveals that large chunks of the code need to be thrown out and replaced, but that's OK.
A good unit test should be written with the mindset of a hacker - how can I break it - rather than just a few assertions. It's not easy to do, and that's why there's so much bad stuff.