fix: replace raise UserWarning with warnings.warn() in verify_report_format (Fixes #8927)

[rtmalikian]

Fixes #8927

Problem

In monai/auto3dseg/utils.py line 287, the code uses raise UserWarning("list length in report_format is not 1"). This raises UserWarning as an exception, which crashes the program. Since UserWarning inherits from Warning → Exception, the raise works but terminates execution.

The function verify_report_format returns bool to indicate format validity — a warning is appropriate here, not a fatal exception. The warnings module is already imported in the file.

Solution

Replace raise UserWarning(...) with warnings.warn(..., stacklevel=2):

# Before (crashes):
raise UserWarning("list length in report_format is not 1")

# After (warns):
warnings.warn("list length in report_format is not 1", stacklevel=2)

Verification

Confirmed that:

• raise UserWarning(...) crashes the program (raises as exception)
• warnings.warn(...) correctly emits a UserWarning without crashing
• The file passes syntax validation
• warnings is already imported in the file

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About the Author: Raphael Malikian — Clinical AI Solutions Architect. I specialise in building and fixing AI/ML systems for healthcare, including vector databases, RAG pipelines, and clinical NLP. If you need help with your project or think I can add value to your organisation, feel free to reach out — I'd love to connect.

📧 rtmalikian@gmail.com
🔗 GitHub: https://github.com/rtmalikian
🔗 LinkedIn: http://www.linkedin.com/in/raphael-t-malikian-mbbs-bsc-hons-71075436a

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Disclosure: This code was developed with assistance from mimo-2.5-pro (Xiaomi) via Hermes Agent (Nous Research). All changes were reviewed, tested against the actual codebase, and verified for correctness.

Changelog

Date	Change	Author
2026-06-18	Initial fix: replace raise UserWarning with warnings.warn()	rtmalikian
2026-06-18	Added DCO sign-off to commit	rtmalikian
2026-06-18	Updated PR documentation with changelog	rtmalikian

Files Changed

• monai/auto3dseg/utils.py — Changed raise UserWarning(...) to warnings.warn(...) in verify_report_format()

Verification

• ✅ Function no longer crashes on invalid report format
• ✅ Warning is emitted instead of raising exception
• ✅ Return value (bool) still indicates format validity
• ✅ DCO sign-off present on all commits

[coderabbitai]

📝 Walkthrough

Walkthrough

In monai/auto3dseg/utils.py, the verify_report_format function no longer raises UserWarning when a nested report_format list length is not exactly 1. It now calls warnings.warn(..., stacklevel=2) instead, turning a fatal exception into a non-fatal runtime warning.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: replacing raise UserWarning with warnings.warn() in the verify_report_format function.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.
Description check	✅ Passed	PR description comprehensively covers the problem, solution, verification, and includes detailed changelog with DCO sign-off confirmation.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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