PyUnit is a unit testing framework that was based on a Java toolkit called JUnit. It is now part of the Python distro, and it's called the unittest module.
It's a pretty light framework--it gives you some assert methods and some methods to build up suites of tests, and then you run the tests, and it gives you stats.
We have used it on the WikiOutliner project. -- SteveHowell
Here's a quick PyUnitHowto. --AdamFeuer
These days I prefer py.test: http://codespeak.net/py/current/doc/test.html --BrianDorsey