[Python] How to use pytest to assert NO Warning is raised

I want to ensure that no warning at all is raised in one assertion.

Could not find any explicit answer in pytest documentation about warnings. (dead link, the 3.2.* doc is not available anymore).

I've tried this, thinking maybe None would mean "nothing":

def test_AttrStr_parse_warnings():
"""Check _AttrStr.parse() raises proper warnings in proper cases."""
with pytest.warns(None):
_AttrStr('').parse()


but this assertion is also always correct, for instance, the test does not fail, even if a warning is actually raised:

def test_AttrStr_parse_warnings():
"""Check _AttrStr.parse() raises proper warnings in proper cases."""
with pytest.warns(None):
_AttrStr('').parse()
warnings.warn('any message')

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