mutmut run leads to hardcoded error in 2.4.2 about mutmut

[boxed]

Well there really shouldn't be any case where mutmut doesn't know where the tests are. That would break the logic that makes mutmut smart about what to rerun and not.

That being said, the hard crash like this isn't good. It would be better if it printed an error message saying it can't find the tests and ask you to add the required config in setup.cfg

[nkuttler]

Does mutmut attempt to detect test directories? I see https://github.com/boxed/mutmut/blob/master/mutmut/__main__.py#L119 which only seems to find tests in the current directory. Would it not be preferable to use the standard unittest test discovery, if possible?

[nkuttler]

Fwiw, using unittest.TestLoader().discover(path) or something similar might be preferable to find test dirs. I could look into getting the directories from that.

[boxed]

That might work for unittest, but it's not a general solution. mutmut doesn't know about what test framework you're using.

[nkuttler]

Automatic discovery for some users still sounds like an improvement to me? Not sure if I should look into it any further though as it's not general, which doesn't seem possible anyway.

[boxed]

Yea.. I'm fine with doing that also.

[l0b0]

Looks like the regression happened in 2.4.1 - a Dependabot PR which only updates mutmut 2.4.0 to 2.4.1 broke my project. Not sure what the workaround is.