I'm trying to get started with unit testing in Python and I was wondering if someone could explain the advantages and disadvantages of doctest and unittest.  
What conditions would you use each for?
I almost never use doctests. I want my code to be self documenting, and the docstrings provide the documentation to the user. IMO adding hundreds of lines of tests to a module makes the docstrings far less readable. I also find unit tests easier to modify when needed.
Python - doctest vs. unittest