def add(x,y):
    """
    >>> add(5,6)
    11
    """
    return x+y

if __name__ == "__main__":
    import doctest
    doctest.testmod()

http://snipplr.com/users/stoyan/

This is going to run all doctests for all methods in a module. Doctests are a beautiful thing. 
Note: doctest will only complain if a test fails. If you see on output then all your tests must have passed.

Running Doctest/Docutils

python

Python