[gumpy] link: dive into python

[Leo Simons <le...@apache.org>]

http://diveintopython.org/toc.html

has a chapter on unit testing

http://diveintopython.org/roman_divein.html

which describes basic unit testing (with python's unittest.py) rather 
brilliantly well.

- Leo

PS: tell me if I should stop posting links; I'll just spam Nicola Ken 
with em ;)