Prevent unimported warnings @ pytest-xdist workers #695
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Pull Request Overview
This PR suppresses spurious “unimported source” warnings when collecting coverage under pytest-xdist workers.
- Disables the private
_warn_unimported_sourceflag on the coverage object inDistMaster.start(). - Ensures coverage collection proceeds without warnings in parallel test sessions.
Comments suppressed due to low confidence (1)
src/pytest_cov/engine.py:453
- Add a test to verify that 'unimported source' warnings are suppressed under xdist worker mode to guard against regressions.
self.cov._warn_unimported_source = False
webknjaz
commented
Jun 6, 2025
| @@ -450,6 +450,7 @@ def start(self): | |||
| data_suffix=_data_suffix(f'w{self.nodeid}'), | |||
| config_file=self.cov_config, | |||
| ) | |||
| self.cov._warn_unimported_source = False | |||
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This should probably include all those other hacks, after all:
Suggested change
| self.cov._warn_unimported_source = False | |
| self.cov._warn_no_data = False | |
| self.cov._warn_unimported_source = False | |
| self.cov._warn_preimported_source = False |
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Perhaps, but without a test triggering these warnings you will never really know what effect this will have.
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Yeah, I only know that only one has a visible effect of suppressing a false negative in ansible-pylibssh. I've been trying to think of a reliable test but no luck so far.
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Ref #693
This fixes #693 (comment) for me.
Actually, locally, I can also drop these private attribute assignments from
DistMasterand it works with just disabling a single warning on the worker.However, when I tried doing this in the project (and not in site-packages of where I'm hitting the problem), it breaks
tests/test_pytest_cov.py::test_xdist_no_data_collectedso I didn't include those changes.I was hoping that you @ionelmc could take a look and maybe come up with some explanation of why this is happening.
Coverage is being collected and reported, but at the time
coveragepyis looking intosys.modules, the module isn't there. I think xdist makes it unpredictable whether the coverage object in master or in the worker would hit this code path. It probably makes sense to disable this warning when under xdist for workers too. It's unreliable at best in such a setup.