Ignore coverage of untaken branches in cudf-polars timezone handling

[wence-]

Description

On some of the CI systems these branches can never be taken.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 59dc98ec-3b06-4263-b82a-af5934585b7e

📥 Commits

Reviewing files that changed from the base of the PR and between a8ad204 and b9d6b56.

📒 Files selected for processing (1)

• python/cudf_polars/cudf_polars/dsl/expressions/datetime.py

Included review availability: Your plan provides up to 12 included reviews per hour; 11 remain after this review.

---

📝 Summary

Summary by CodeRabbit

• Tests
  • Updated code coverage annotations for timezone transition fallback branches.
  • No user-visible runtime behavior changes.

Walkthrough

The change adds coverage exclusions to three empty-timezone-transition fallback branches in the datetime expression implementation. Runtime behavior remains unchanged.

Changes

Datetime coverage annotations

Layer / File(s)	Summary
Fallback coverage exclusions python/cudf_polars/cudf_polars/dsl/expressions/datetime.py	Three empty-transition fallback branches now use # pragma: no cover. Their existing return values and ambiguity handling remain unchanged.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to b9d6b

This change excludes unreachable timezone fallback branches from coverage measurement while preserving datetime behavior. No current merge-blocking risk is identified.

Suggested reviewers: mroeschke

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: excluding untaken branches from coverage in cudf-polars timezone handling.
Description check	✅ Passed	The description explains why the coverage exclusions are needed and relates directly to the changeset.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[wence-]

/merge