Crash when collecting reports

[ericvergnaud]

pytest-cov crashes when pytest-asyncio is installed and used (i.e. some tests are `async).

The crash is as follows:

DataError: Can't combine statement coverage data with branch data
For more information see https://pluggy.readthedocs.io/en/stable/api_reference.html#pluggy.PluggyTeardownRaisedWarning
  config.hook.pytest_runtestloop(session=session)

From the reference, it seems the culprit is pytest-asyncio using an old style event loop ?

[seifertm]

Can you provide a small example that reproduces the error?

[ericvergnaud]

Mmm... can't reproduce it anymore. Maybe it was caused by a corrupt venv...

[ericvergnaud]

I can reproduce it again, and also found the following:
nedbat/coveragepy#512
The code I'm testing creates child processes, so it smells like the issue is not within asyncio, although disabling it prevents execution of the code that triggers it

[seifertm]

@ericvergnaud Thanks for the update. Let us know if there's anything to investigate from pytest-asyncio side.