sympy/sympy — pull request #2030 by hacman (2013-04-20 15:27:41+00:00)
Title: testing on files you've changed

This was born somewhat from necessity. It conveniently tests the files you have changed in your git repo (for both doctests and regular tests). Heuristics on finding regular (non-doc) tests could probably be improved, but SymPy seems to follow this convention well.