Type inference tests

[claudevdm]

Documents how typevars, typehint decorators and typehint inference works.

#36775

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[gemini-code-assist]

Summary of Changes

Hello @claudevdm, 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 clarity and robustness of type inference within Apache Beam's Python SDK. It introduces detailed documentation for the _infer_result_type function, explaining the mechanics of type variable binding and substitution. Additionally, new test cases have been added to thoroughly verify the behavior of type hints in various PTransform configurations, ensuring predictable type inference outcomes and highlighting current limitations.

Highlights

• Enhanced Type Inference Documentation: A comprehensive docstring has been added to the _infer_result_type function in pipeline.py, detailing how type variables, typehint decorators, and type inference work, including binding algorithms and examples.
• New Type Inference Test Cases: Three new test cases were introduced in ptransform_test.py to validate type variable binding behavior in PTransforms, covering scenarios with complete hints, missing input hints, and missing output hints on child transforms.
• Dependency Cleanup: Unused FrozenSet and Iterable imports were removed from pipeline.py to streamline dependencies.

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[claudevdm]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds comprehensive documentation to the _infer_result_type method, clarifying the mechanics of type inference with type variables in Beam. It also introduces new tests to validate this behavior. The changes are a great improvement to the codebase's documentation and test coverage. I have a couple of minor suggestions for one of the new tests to improve clarity and prevent potential confusion.

[claudevdm]

R: @damccorm

[claudevdm]

R: @jrmccluskey can you please check my understanding?

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

[jrmccluskey]

This aligns with my awareness of this mechanism (and actually expands upon it, I was unaware of the switching funcitonality in the [V, K] case.) Only problem is the whitespace precommit

[jrmccluskey]

LGTM, thanks!