Fix namespace parsing to correctly discover package namespaces instead of simple string replacement

[Copilot]

The namespace parsing in parse_pyproject and parse_setup_py functions was using a naive approach of simply replacing - with . in package names to determine namespaces. This approach fails for packages with complex namespace structures.

For example, the package azure-eventhub-checkpointstoreblob has:

• Package name: azure-eventhub-checkpointstoreblob
• Actual namespace: azure.eventhub.extensions.checkpointstoreblob
• Incorrect simple replacement: azure.eventhub.checkpointstoreblob

Changes Made

1. Added discover_namespace() function - Walks through the package directory structure to find __init__.py files and discovers the actual namespace by examining the module hierarchy
2. Added _set_root_namespace() helper - Determines if an __init__.py file contains substantial content vs just namespace extension calls (like extend_path)
3. Updated parse_pyproject() - Now uses namespace discovery before falling back to simple string replacement
4. Updated parse_setup_py() - Enhanced metapackage handling to also use namespace discovery
5. Comprehensive test coverage - Added tests for the specific issue case, edge cases, and fallback scenarios

Validation Results

• ✅ azure-eventhub-checkpointstoreblob now correctly resolves to azure.eventhub.extensions.checkpointstoreblob
• ✅ Backward compatibility maintained for packages where simple replacement was already correct
• ✅ All existing tests pass (14/14 tests passing)
• ✅ Both setup.py and pyproject.toml parsing paths work correctly
• ✅ Graceful fallback when namespace discovery fails

The implementation follows the logic provided in the issue description and ensures robust namespace discovery while maintaining backward compatibility.

Fixes #41941.

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[scbedd]

LGTM now.