Hello! In version 1.X of Pants, the target

python_tests

has the property `coverage`:

coverage: A list of the module(s) you expect for this test target to cover. Usually, Pants and pytest-cov can auto-discover this if your tests are located in the same folder as the python_library code, but this is useful if the tests are not collocated.

However, in version 2.X, I noticed there’s no such property. What’s the equivalent one in Pants 2.X?

Hello! Yes, it's much simpler now. See https://www.pantsbuild.org/docs/how-to-upgrade-pants-2-0#coveragepy-support-was-redesigned-v1-engine-vs-v2-engine

Ahh,

--coverage-py-filter

, correct?

Yeah if you want to filter rather than all files in the chroot, you use that option. Although note that pants runs in a chroot (tmpdir), so it already only reports on files in the transitive closure of your particular tests https://www.pantsbuild.org/docs/python-test-goal#coverage

And can’t we apply the coverage to just a subset of the transitive closure? 😅

Yes, via that option One of the big differences with the redesign is that it was really tricky to get the coverage field on Python_tests to work correctly and the results were almost always under-reporting. You can still report on as little as you want, but now it's more obvious

OK, but now I need to invoke

pants

for each of the stacks, with a different value for

--coverage-py-filter

, right?

Could you still do one run, but allowlist everything except for common? Note that you can pass multiple values for --filter, it's a list option

I see! Let me give that a try then

You're welcome! Also reminder that Pants calls

coverage combine

to merge all the distinct test results into one single report. So, if you're running all your tests, it may be useful to still include common The results would be misleading when you do a run locally on a subset of your tests, but that's probably fine - only care about the number in CI that runs over everything

The issue I’m having is that common is included in the reports, even though we’re mocking any references to other stacks 🤔. Previously, when we were using 1.28, we were using the property

coverage

in

python_test

, as this allowed us to apply the coverage threshold per stack. I was hoping the behaviour would stay the same, however, you raised the concern that the coverage could not be correct. I will try the

coverage-py-filter

option.