feat(gazelle): Add ancestor conftest.py files

[thejcannon]

Re-introduces the gazelle behavior of adding conftest targets to tests so that
they inherit parent directory configs.

Fixes #3497

[gemini-code-assist]

Summary of Changes

Hello @thejcannon, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the integration of pytest with Gazelle's Python extension by enabling the automatic discovery and inclusion of conftest.py files from parent directories. This ensures that py_test rules correctly inherit shared fixtures and configurations, leading to more robust and maintainable test setups. The change addresses a previous limitation where only conftest.py files in the immediate directory were considered, streamlining the dependency management for pytest users.

Highlights

• Ancestor conftest.py Discovery: Implemented a new function, findConftestPaths, which efficiently traverses parent directories to locate all relevant conftest.py files from the current package up to a specified project root.
• Enhanced py_test Dependency Resolution: Gazelle's Python extension now automatically adds all discovered ancestor conftest.py files as dependencies for py_test rules, in addition to sibling conftest.py files.
• Bug Fix: This change resolves issue Bug/regression: Ancestor conftest inclusion #3497, addressing a limitation where py_test rules did not correctly recognize conftest.py files located in parent directories.

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[gemini-code-assist]

Code Review

This pull request introduces a valuable feature to Gazelle by adding support for ancestor conftest.py files, which aligns Gazelle's behavior more closely with Pytest's discovery mechanism. The implementation is clean and effective. The new findConftestPaths function correctly traverses the directory hierarchy, and the logic in GenerateRules has been nicely refactored to incorporate this. The updated test outputs confirm the change works as expected. Overall, this is a well-executed improvement.

[rickeylev]

@dougthor42 : I see you removed it from the merge queue. Do you want me to undo my review and let you handle this PR? I just approved because I saw it requested for 1.8-rc2. I'm fine with omitting this from RC2 if you want time to review.

[dougthor42]

N.B.: There are valid cases where there exists one or more conftest.py files that are above pythonProjectRoot:

MODULE.bazel
conftest.py
src/             # gazelle:python_root
  package1/
    subpackage/
      conftest.py
      foo.py
      foo_test.py
  package2/
    ...

I think we should ignore the pythonProjectRoot and only stop at the Bazel module root when searching.

[dougthor42]

Can you explain why you changed from pyTestTarget.addModuleDependency() to pyTestTarget.deps.Add()?

letting doug approve/review

[dougthor42]

I see you removed it from the merge queue. Do you want me to undo my review and let you handle this PR? I just approved because I saw it requested for 1.8-rc2. I'm fine with omitting this from RC2 if you want time to review.

It depends on how quickly the requested change can be added.

The core idea of it and the implementation are great, but there's a case that I would think is common.

I've marked Request Changes but can switch to "Approved and trust it gets fixed before merge" if that would be better.

[rickeylev]

I'm tagging RC2 now, so I'll just omit this PR for now.

[thejcannon]

I'll get to the comments tonight hopefully when I crack open my laptop.

It's also no rush on my end, I've already patched my way to using it at $work.