Remove diff cover

[ewjoachim]

This PR removes diff-cover from the codebase:

• Computes the list of added lines from git diff
• Creates a DiffCoverage object from a Coverage object, restricting lines to the ones added
• Recomputes all derived metrics from the base ones

The nice thing is that the tests barely need to change.

We bump the docker image version number in the process, but I believe the old action will run on the new image, and vice versa (thanks to the pip install . that we left in Dockerfile) so I don't think we need to do anything specific for this to work.

[github-actions]

End-to-end public repo

[ewjoachim]

Ha of course.
The CI of e2e fail because:

ERROR: failed to solve: ewjoachim/python-coverage-comment-action-base:v4: docker.io/ewjoachim/python-coverage-comment-action-base:v4: not found

[ewjoachim]

subprocess.CalledProcessError: Command '('git', 'diff', '--unified=0', 'origin/main', '--', '.')' returned non-zero exit status 128.
fatal: bad revision 'origin/main'

Hmm... Is it a problem of a missing fetch ? But why didn't we have that with diff cover ? Time to explore...

[ewjoachim]

https://github.com/py-cov-action/python-coverage-comment-action/pull/257/files#diff-5327f4a45499e33cab8758f61e6b738fc200a07b00c58fc231f37a3142461ac7L215 That's the reason.

[ewjoachim]

Ow damn you already have a branch for doing that :( https://github.com/py-cov-action/python-coverage-comment-action/tree/replace-diff-cover

Sorry about the duplicated work !

[kieferro]

Sorry about the duplicated work !

It's of course not ideal, but no big problem, I had neglected the branch a bit anyway, because we had more important things at the time and and then I didn't deal with it. But the fact that I had already thought about it makes the review process easier for me.

How do we want to proceed, do you want to get the CI passing first or should I review it now?

[ewjoachim]

I think the only thing needed is for me to push the missing git fetch. Let's say you're welcome to review once it's green :)

[github-actions]

Coverage report

The coverage rate went from 100% to 100% ➡️
The branch rate is 100%.

100% of new lines are covered.

Diff Coverage details (click to unfold)

coverage_comment/main.py

100% of new lines are covered (100% of the complete file).

coverage_comment/coverage.py

100% of new lines are covered (100% of the complete file).

[ewjoachim]

All green, rebased conflicts resolved, all yours :)

[ewjoachim]

Ok, I think all your comments have been addressed.

[kieferro]

Yes, looks good