TEST: Reuse Python test inputs

[vyasr]

Description

Reuses read-only test data across indexing and reduction tests, avoiding repeated device allocations and conversions while preserving the existing assertions and parameter coverage.

Checklist

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

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📥 Commits

Reviewing files that changed from the base of the PR and between e78c254 and c2da4d7.

📒 Files selected for processing (5)

• python/cudf/cudf/tests/dataframe/indexing/test_iloc.py
• python/cudf/cudf/tests/dataframe/indexing/test_loc.py
• python/cudf/cudf/tests/dataframe/methods/test_reductions.py
• python/cudf/cudf/tests/series/indexing/test_iloc.py
• python/cudf/cudf/tests/series/methods/test_reductions.py

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📝 Summary

Summary by CodeRabbit

• Tests
  • Refactored DataFrame and Series indexing tests to reuse shared, validated pandas and cuDF test fixtures.
  • Consolidated reduction-test inputs into reusable fixtures covering nullable integer and floating-point data.
  • Preserved existing indexing assertions, transformations, reduction coverage, and expected-failure handling.

Walkthrough

The tests now use module-scoped fixtures for shared pandas and cuDF indexing and reduction inputs. Reduction tests receive explicit dataset or dtype information from fixture-generated inputs.

Changes

Test fixture refactor

Layer / File(s)	Summary
MultiIndex indexing fixtures python/cudf/cudf/tests/dataframe/indexing/test_iloc.py, python/cudf/cudf/tests/dataframe/indexing/test_loc.py	Added validated shared MultiIndex pandas/cuDF frames and updated .iloc and .loc tests to consume them.
DataFrame reduction fixtures python/cudf/cudf/tests/dataframe/methods/test_reductions.py	Moved reduction datasets into a fixture that provides dataset IDs and matching pandas/cuDF DataFrames.
Series indexing fixture python/cudf/cudf/tests/series/indexing/test_iloc.py	Added reusable DataFrame builders and a fixture that provides pandas/cuDF pairs to the .iloc test.
Series reduction fixture python/cudf/cudf/tests/series/methods/test_reductions.py	Added parametrized nullable numeric Series inputs and updated the reduction test to consume them.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: mroeschke, galipremsagar

Merge Risk: ⚪ Minimal · up to c2da4

This change only reorganizes existing test setup code to share read-only test data through fixtures, with no changes to production behavior. Verification confirmed the reduction test's updated expected-failure matching still targets the same cases as before, and the shared fixtures are not mutated by the tests that consume them. This is safe to merge.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 25 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: reusing Python test inputs across indexing and reduction tests.
Description check	✅ Passed	The description directly explains the reuse of read-only test data, reduced allocations and conversions, and preservation of test coverage.
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.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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