Do you know the handy coverage.py? It's a useful tool to measure the test coverage of your python program! It supports CPython and PyPy for Python2 and Python3, and integrates with pytest, aswell!
Now, have you ever looked at a long list of uncovered source code lines and despaired? Despair no more! Execute shoot.py on an xml coverage report to receive a random uncovered line of code. Now go write (good) tests!
Usage:
> coverage xml > shoot.py coverage.xml Write a test covering line 127 in file "foo/bar/baz/cookie.py"!