A small unit test example I constructed from Mark Pilgrim's Roman test, however with that classic square. Can you think of something simpler? Unit testing: http://www.cs.helsinki.fi/u/hendry/work/python/squaretest.py What it is testing: http://www.cs.helsinki.fi/u/hendry/work/python/square.py Good docs: http://pyunit.sourceforge.net/pyunit.html#USING Methods needs to begin with test... to run as a unittest !!!!