I need some help with transitive transient test failures in a plugin I wrote (this is actually nearly the same code that’s in PR https://github.com/pantsbuild/pants/pull/16932). I created a sample repo that reproduces the problem I’m seeing here: https://github.com/bryanwweber/pants-dependency-tracking What I find is that if I run

./pants test --force ::

repeatedly, it fails about 3/4 of the time. I have no idea why this is occurring… adding as many output and debugging options as I can from the docs (

--print-stacktrace -ldebug --pex-verbosity=9 --keep-sandboxes=always --no-pantsd --no-local-cache

) and comparing logs between successful and failing runs doesn’t turn up anything obvious. The reason I created this test repo is because in our actual code, I can’t even run the tests due to a dependency inference error:

./pants test  ::
15:48:35.48 [ERROR] 1 Exception encountered:

  UnownedDependencyError: Pants cannot infer owners for the following imports in the target pants-plugins/pep621/pep621_requirements_test.py:tests:

  * .pep621_requirements.PEP621RequirementsTargetGenerator (line: 16)
  * .pep621_requirements.rules (line: 16)

If you do not expect an import to be inferrable, add `# pants: no-infer-dep` to the import line. Otherwise, see <https://www.pantsbuild.org/v2.14/docs/troubleshooting#import-errors-and-missing-dependencies> for common problems.

As near I can tell, the configuration between the repos is the same.

Which platform are you running this on to get the errors?

macOS 12.6, M1

In your demo repo (and thanks for that! makes things so much easier to debug) on my macOS 12.6 M1 I get a slightly different outcome: it failed on the first run, then succeeded after that every time.

Here’s the error. I find the failures are intermittent. If I run a bunch in a row, I’ll get 5 failures, then 3 success, then a few more failures, etc. I also found that running with the

--debug-adapter

and connecting via VSCode, the tests passed every time I tried (maybe 5 times). Obviously, those runs there’s a much longer time taken for the test to run as I’m stepping through… I wonder if time piece is related?

Hmm, yes, I was seeing a similar error, looks like the issue is

tags=('another-tag', 'jupyter', 'jupyter')

vs

tags=('another-tag', 'jupyer')

Yep, that’s what I noticed as the error as well. I’m going to try removing the code from use as a plugin and see if it helps

Oh, interesting, so a conflict between code-as-plugin and the-same-code-under-test

That’s what seems to be the case…

So the suspect code would be pep621_requirements.py:67-76

If I remove the tagging, the tests seem to consistently pass. I wonder if it’s something to do with using a mutable data structure here and overriding parts of it, rather than creating a new object from scratch

Hmmm, looks like a subtle concurrency issue in your test