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Parametrizing a test with an empty list calls ids callback with the private constant NOTSETÂ #13031
Description
I parametrize tests based on a user-provided list. Sometimes this list is empty, which disables some tests as a result. However, I would expect the ids callback that I provide to not be called at all in that case, but it is actually called with the private NOTSET sentinel. As this is not exported, I can't easily check for it in my ids function and return a useless value to match it.
Reproduction:
conftest.py
import logging
def idmap(obj):
logging.info(obj)
def pytest_generate_tests(metafunc):
if "arg" in metafunc.fixturenames:
metafunc.parametrize(
"arg", [], ids=idmap
)test_demo.py
def test_demo(arg):
pass$: pytest --collect-only --log-cli-level=DEBUG
...
INFO root:conftest.py:4 NotSetType.token
...
Python: 3.10.15
pytest: 8.3.4
OS: macOS Sonoma 14.6.1
Activity
RonnyPfannschmidt commentedon Dec 6, 2024
For empty id lists we generate a single test with a warning
mon commentedon Dec 6, 2024
Yes, which is reasonable - but I can't detect this in my ID mapping function because it's a hidden type. Perhaps the sentinel can just be exported? Or don't call the ID map for the "no parametrization" case.
I can make a PR in either case!
RonnyPfannschmidt commentedon Dec 6, 2024
https://github.com/pytest-dev/pytest/blob/main/src%2F_pytest%2Fmark%2Fstructures.py#L182-L186
mon commentedon Dec 6, 2024
I don't quite understand - I don't get access to the ParameterSet, and thus can't see its marks. I simply get
NOTSETpassed to theidscallback. BecauseNOTSETis internal to Pytest, I cannot compare the arg against it nor type annotate my ids function to accept it.RonnyPfannschmidt commentedon Dec 6, 2024
indeed - we should use a string that indicates it
RonnyPfannschmidt commentedon Dec 6, 2024
i have a wip pr that sets the string NOTSET as direct id to avoid this - 'll polish it a litlle and push
fix pytest-dev#13031: use the concrete id NOTSET for the empty parameâĶ
fix pytest-dev#13031: use the concrete id NOTSET for the empty parameâĶ
fix pytest-dev#13031: use the concrete id NOTSET for the empty parameâĶ
fix pytest-dev#13031: use the concrete id NOTSET for the empty parameâĶ
fix pytest-dev#13031: use the concrete id NOTSET for the empty parameâĶ
mon commentedon Dec 22, 2024
Fantastic, thank you so much!
chore(deps): update dependency pytest to v9 (#305)