Currently, Travis CI runs C coverage and Python coverage jobs on all pull requests. This is a waste of resources: we should only run these jobs on branches like master.

Attached PR skips these jobs on pull requests.

Not only it's a waste of resources, but it seems like it's not longer possible to merge a PR as soon as Travis CI required jobs pass: a PR can only be merged when *all* Travis CI jobs complete. Problem: while a full test suite run takes around 20 min, coverage jobs take longer than 40 minutes.

By the way, the C coverage job fails with timeout, but that's a different issue.

Concrete issue: on my PR 20915, Travis CI mandatory jobs completed successfully but I wasn't able to merge the PR since GitHub says "travis-ci/pr Pending — The Travis CI build is in progress".

I cancelled the last running coverage job... but I was still unable to merge the PR, since Travis CI didn't report the status to GitHub.

I had to reschedule all Travis CI jobs...

See also "Travis CI doesn't report its status or doesn't run on Python pull requests":
https://github.com/python/core-workflow/issues/371

See also bpo-40237: "Test code coverage (C) job of Travis CI fails on test_distutils which creates _configtest.gcno file".

Documentation about skipping jobs on pull requests:
https://docs.travis-ci.com/user/pull-requests/#how-pull-requests-are-built

I don't think that the following method works for the issue:

"To only build on push events not on pull requests, disable Build on Pull Requests in your repository settings."

That would disable all jobs, not only coverage jobs.

New changeset fc710ee266e9461fdba9933ec6004318db588820 by Victor Stinner in branch 'master':
bpo-40993: Don't run Travis CI coverage on PRs (GH-20916)
https://github.com/python/cpython/commit/fc710ee266e9461fdba9933ec6004318db588820

New changeset 3cf809475a93228a3cb310b4d10d38f3b9d44c1f by Miss Islington (bot) in branch '3.9':
bpo-40993: Don't run Travis CI coverage on PRs (GH-20916)
https://github.com/python/cpython/commit/3cf809475a93228a3cb310b4d10d38f3b9d44c1f

New changeset 071bed842eeff9673bc5c4f64e3916a151132d2a by Miss Islington (bot) in branch '3.8':
bpo-40993: Don't run Travis CI coverage on PRs (GH-20916)
https://github.com/python/cpython/commit/071bed842eeff9673bc5c4f64e3916a151132d2a

> Attached PR skips these jobs on pull requests.
I am not familiar with travis ci. coverage jobs can tell us how many features need add unit tests. Can we use other CI services to do this job? MAYBE in checks gate or something other services like buildbot.python.org?

> coverage jobs can tell us how many features need add unit tests.

Coverage jobs are still run with my changes. https://codecov.io/gh/python/cpython is still updated.

My change only stops running coverage jobs on pull requests.

> Coverage jobs are still run with my changes.
> https://codecov.io/gh/python/cpython is still updated.

Copy that, thanks.