pytest.warns check for class equality and not subclass relationship. This snippet for example fails:

import warnings

import pytest


with pytest.warns(Warning):
    warnings.warn('user', UserWarning)

This was slightly surprising to me since my expectation was that it would be similar to pytest.raises where you can check for a base class:

import pytest


with pytest.raises(Exception):
    raise ValueError()

What do you guys think? After all you can always use with pytest.warns(None) as warninfo and check issubclass(warninfo[0].message, a_warning_class) if you want to check a subclass relationship. At the same time, I don't really how it would hurt to check subclass relationship.

I guess that is just a matter of changing this line by:

if not any(issubclass(r.category, each) for each in self.expected_warning for r in self):

I am willing to open a PR about this if you think it is worth it.