Merge pytest-cov and coveragepy

ionelmc commented 5 years ago

I've talked a bit to @nedbat and he is open to the idea of moving the wrapper that is pytest-cov inside https://github.com/nedbat/coveragepy

The impending release of coveragepy 5.0 and various features (like @graingert 's multiple fail-under support) have made clear that it's a good time to seriously consider merging the projects.

I've open this issue to discuss details and get people to agree about various organizational and technical details - basically to see if this is really possible.

Writing down my ideas, comment if you thoughts regarding any of them:

the xdist/subprocess support code will replace coveragepy's own subprocess support (which is a bit more limited)
pytest-cov's test suite will be simpler since we won't need to integration test against several coveragepy versions
@graingert's PR would be put on hold (in the idea that the feature would be in coveragepy's core - I think that's a win even if it's a bit more complicated to do)
@nedbat, @pytest-dev/pytest-cov-admin, @blueyed and whoever I might have missed will need to agree on a way to maintain the new pytest component of coveragepy (hopefully just a simple release/pr process so we don't have a huge mess or overload Ned with unwanted work).

TODO for me: do a proof of concept with a pytest plugin inside coveragepy to see that we don't have some blocking issue.

nedbat commented 5 years ago

the xdist/subprocess support code will replace coveragepy's own subprocess support (which is a bit more limited)

I don't understand the implications of this: does it mean that subprocesses are only measured if running under pytest?

ionelmc commented 5 years ago

I don't understand the implications of this: does it mean that subprocesses are only measured if running under pytest?

I would mean we're going to change the names and/or values of some env vars. It should not make coveragepy lose features without pytest as pytest_cov.embed doesn't have any pytest coupling.

ionelmc commented 5 years ago

Hmmm, maybe @pytest-dev/core might want to know about this merge idea.

pytest-dev / pytest-cov

Merge pytest-cov and coveragepy #331