Skip test_string_agg_aliases on older SQLite versions

[aryansri05]

Skips test_string_agg_aliases[STRING_AGG] and test_string_agg_aliases[GROUP_CONCAT]
in the cudf-polars-polars test suite by adding them to TESTS_TO_SKIP in
inject_gpu_engine.py.

These tests fail with sqlite3.OperationalError: near "ORDER": syntax error because
the CI environment's SQLite version predates 3.44.0, which is when support for
ORDER BY inside GROUP_CONCAT/STRING_AGG aggregates was introduced. This is a
CI environment constraint, not a bug in cuDF-polars logic.

TODO: remove the skip entries once CI upgrades to SQLite >= 3.44.0.

Closes #22850
Checklist:

I am familiar with the Contributing Guidelines
New or existing tests cover these changes — (N/A: this is a test skip for a CI env limitation)
The documentation is up to date — (N/A: no API/behavior changes)

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📥 Commits

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📒 Files selected for processing (1)

• python/cudf_polars/cudf_polars/testing/inject_gpu_engine.py

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📝 Walkthrough

Summary by CodeRabbit

• Tests
  • Configured additional test cases to skip during CI runs to ensure compatibility with current environment dependencies.

Walkthrough

The PR adds two SQL test case skip entries to address SQLite version incompatibility in CI. The tests test_string_agg_aliases[STRING_AGG] and test_string_agg_aliases[GROUP_CONCAT] are skipped because the CI SQLite version (< 3.44.0) does not support ORDER BY clauses within string aggregation functions.

Changes

SQL Test Skip Configuration

Layer / File(s)	Summary
String aggregation test skip entries python/cudf_polars/cudf_polars/testing/inject_gpu_engine.py	Two test_string_agg_aliases test variants (STRING_AGG and GROUP_CONCAT) are added to TESTS_TO_SKIP list to skip on CI due to SQLite < 3.44.0 not supporting ORDER BY in string aggregation.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• rapidsai/cudf#22605: Also modifies TESTS_TO_SKIP in the same file to exclude SQL test cases incompatible with CI test infrastructure.

Suggested labels

Python, improvement, non-breaking, cudf-polars

Suggested reviewers

• vyasr
• jameslamb
• TomAugspurger

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: skipping test_string_agg_aliases tests on older SQLite versions.
Description check	✅ Passed	The description clearly explains why the tests are being skipped, references the CI SQLite version limitation, and provides a TODO for future removal.
Linked Issues check	✅ Passed	The PR directly addresses issue #22850 by implementing the requested temporary skip for failing tests due to SQLite version constraints.
Out of Scope Changes check	✅ Passed	All changes are scoped to addressing the test failures in issue #22850; only the TESTS_TO_SKIP list is modified.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[TomAugspurger]

Thanks @aryansri05. I'm going to handle this in #22870, which does things a bit differently to cover all the failing tests and makes the skip conditional on the version of python / sqlite.