TEST: Merge import subprocess checks

[vyasr]

Description

Merge the two isolated import subprocess checks. The existing no-device subprocess now also asserts that importing cuDF does not import pyarrow._s3fs.

Both contracts are still verified after the same cold, isolated cuDF import, so this removes only a redundant Python startup and not any assertion.

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 623f961 and f920201.

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• python/cudf/cudf/tests/test_no_device.py

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📝 Summary

Summary by CodeRabbit

• Tests
  • Updated import validation to confirm cuDF does not load S3 filesystem components during import.
  • Removed a redundant S3-related import test and cleaned up unused test dependencies.
  • Updated no-device test coverage to verify expected import behavior.
• Chores
  • Updated copyright notices with current attribution details and “All rights reserved.”

Walkthrough

The pull request removes an obsolete S3 import test and extends the no-device cuDF import test to verify that pyarrow._s3fs is not loaded. It also updates SPDX attributions.

Changes

cuDF import test validation

Layer / File(s)	Summary
No-device import validation python/cudf/cudf/tests/test_no_device.py, python/cudf/cudf/tests/input_output/test_s3.py	The subprocess test checks that pyarrow._s3fs is absent from sys.modules. The obsolete S3 import test and unused imports are removed. SPDX attributions are updated.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to f9202

This change consolidates cuDF import-invariant coverage while preserving the no-device check and verifying that importing cuDF does not load pyarrow._s3fs. No current merge-blocking risk remains.

Suggested reviewers: mroeschke

🚥 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 2 functions across 2 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 describes the main change: merging two import subprocess checks.
Description check	✅ Passed	The description directly explains the merged subprocess checks, retained assertions, and reduced interpreter startup cost.
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.

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[bdice]

Does this test take a lot of time? I agree these can be combined but we are really testing two different things (s3fs and no devices) that now appear under a single test name.

[vyasr]

Does this test take a lot of time? I agree these can be combined but we are really testing two different things (s3fs and no devices) that now appear under a single test name.

This is a pretty tiny improvement yeah. I added it since at this point I'm taking every win I can, but it's miniscule on the scale of everything else. These tests take 3-4s each, so combining them shaves that off. Since this PR is already up, I'll just add some helpful comments and rename the test for clarity, but if we find it odd later I'm happy to split it back out.

[vyasr]

/merge