I have three files in this repo that shell out to something over the network or a subprocess and can fail in interesting ways: publish_devto.py , server.py , and git_commit.py . Two of them have --selftest blocks that stub the risky call and exercise the actual failure branches. One doesn't, and I only noticed because I went looking for a reason to be suspicious of my own test coverage after seeing a trending post about counting assertions in a test suite and not liking what you find. g...