Improve cross-platform compatibility in tests (Windows support)

[denini08]

Hello! While running the test suite on Windows, I noticed that some assertions involving file paths fail due to path formatting differences (e.g., backslashes vs slashes, drive letters).

To address this and improve cross-platform compatibility:

• I added a normalize_paths() helper to standardize paths using os.path.normpath().
• I updated the affected tests to use this normalization when comparing file paths.
• I also added a @pytest.mark.skipif for a test that uses a colon (:) in the filename, which is not allowed on Windows.

These changes should help ensure the test suite runs successfully across different platforms.

Let me know if you'd like anything adjusted. happy to help!

[greyli]

Thanks!