Fix #7980: Enhanced image writer error messages with actionable installation guidance

[iloveme81189-del]

Fixes #7980

Description

This pull request improves the error handling in MONAI's image writer backend resolution module. When a suitable backend is missing for a given file extension, it now provides detailed error messages with actionable installation suggestions for common image formats:

• .nii/.nii.gz → advises installing nibabel
• .png, .jpg, .jpeg, .bmp → advises installing Pillow
• .mha, .mhd → advises installing itk

Changes

• Updated resolve_writer function to append extension-specific package installation hints to OptionalImportError.
• Added tests to simulate missing writer backend scenarios and verify error messaging.
• Cleaned up runtime version introspection in tests to separate scope and maintain clarity.

Checklist

• Bug fix (non-breaking change which fixes an issue)
• Documentation update (if applicable)
• Tests added and passing

Impact

This update improves user and developer experience by reducing troubleshooting time in medical imaging pipelines through clear, prescriptive error guidance.

[coderabbitai]

Walkthrough

Adds runtime version printing in test_env.py by importing torch and monai and printing their versions. Introduces a test in test_writer_error.py that imports writer-resolution utilities from monai.data.image_writer, saves and clears fallback writers to simulate no writer support, attempts to resolve a writer with error_if_not_found=True, catches OptionalImportError and prints diagnostics, then restores the original fallback writers in a finally block.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Pre-merge checks and finishing touches

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Out of Scope Changes Check	⚠️ Warning	The addition of runtime version introspection in test_env.py printing PyTorch and MONAI versions is unrelated to enhancing image writer error messages and falls outside the linked issue objectives.	Move the version introspection changes to a separate housekeeping PR or remove them from this branch to keep the scope focused.
Description Check	⚠️ Warning	The PR description deviates from the repository template by using custom headings and omitting the required “Types of changes” section and its checkboxes, and does not match the exact structure of the template.	Reformat the description to follow the provided template exactly, adding the “Types of changes” section with the defined checklist items and using the prescribed headings.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title accurately summarizes the primary change of enhancing image writer error messages with actionable installation guidance and correctly references the linked issue.
Linked Issues Check	✅ Passed	The changes implement extension-specific installation hints in the resolver and add tests to simulate missing backends as described in issue #7980, fully satisfying the linked issue objectives.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Knowledge base: Disabled due to Reviews -> Disable Knowledge Base setting

📥 Commits

Reviewing files that changed from the base of the PR and between 2d7d4e8 and 14ccd76.

📒 Files selected for processing (2)

• test_env.py (1 hunks)
• test_writer_error.py (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (2)

• test_writer_error.py
• test_env.py

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Actionable comments posted: 5

📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Knowledge base: Disabled due to Reviews -> Disable Knowledge Base setting

📥 Commits

Reviewing files that changed from the base of the PR and between 69f3dd2 and 2d7d4e8.

📒 Files selected for processing (2)

• test_env.py (1 hunks)
• test_writer_error.py (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

**/*.py

⚙️ CodeRabbit configuration file

Review the Python code for quality and correctness. Ensure variable names adhere to PEP8 style guides, are sensible and informative in regards to their function, though permitting simple names for loop and comprehension variables. Ensure routine names are meaningful in regards to their function and use verbs, adjectives, and nouns in a semantically appropriate way. Docstrings should be present for all definition which describe each variable, return value, and raised exception in the appropriate section of the Google-style of docstrings. Examine code for logical error or inconsistencies, and suggest what may be changed to addressed these. Suggest any enhancements for code improving efficiency, maintainability, comprehensibility, and correctness. Ensure new or modified definitions will be covered by existing or new unit tests.

Files:

• test_writer_error.py
• test_env.py

[iloveme81189-del]

the 4 minor issues are resolved