Formatting not applied when source file autosaved

[bobf32]

Diagnostic Data

• Python version (& distribution if applicable, e.g., Anaconda): 3.12
• Type of virtual environment used (e.g., conda, venv, virtualenv, etc.): venv
• Operating system (and version): Win 11 Enterprise
• Version of tool extension you are using: v2024.4.0

Behaviour

Expected Behavior

With auto save on in VSCode, Black formatting is not applied on auto saves.

Actual Behavior

Nothing. Blaxk formatting only occurs when pressing Ctrl-S.

Reproduction Steps:

Load Python file
Enabled VSCode auto save
Make a change that Black would correct
Observe file is auto saved but no formatting occurs
Press Ctrl-S
Observe Black formatting takes place.

Logs:

2024-10-15 15:06:52.624 [info] [Trace - 3:06:52 PM] Received response 'textDocument/formatting - (2)' in 37ms.
2024-10-15 15:06:52.670 [info] [Trace - 3:06:52 PM] Sending notification 'textDocument/didChange'.
2024-10-15 15:06:58.692 [info] [Trace - 3:06:58 PM] Sending notification 'textDocument/didChange'.
2024-10-15 15:07:01.176 [info] [Trace - 3:07:01 PM] Sending notification 'textDocument/didChange'.
2024-10-15 15:07:03.489 [info] [Trace - 3:07:03 PM] Sending request 'textDocument/formatting - (3)'.
2024-10-15 15:07:03.491 [info] [Trace - 3:07:03 PM] Received notification 'window/logMessage'.
2024-10-15 15:07:03.491 [info] /home/xxxxx/venv_312/bin/python3.12 -m black --stdin-filename /home/xxxxx/python/scratch.py -
2024-10-15 15:07:03.491 [info] [Trace - 3:07:03 PM] Received notification 'window/logMessage'.
2024-10-15 15:07:03.491 [info] CWD formatter: /home/xxxxx/python
2024-10-15 15:07:03.520 [info] [Trace - 3:07:03 PM] Received notification 'window/logMessage'.
2024-10-15 15:07:03.520 [info] reformatted /home/xxxxx/python/scratch.py

All done! ✨ 🍰 ✨
1 file reformatted.

2024-10-15 15:07:03.524 [info] [Trace - 3:07:03 PM] Received response 'textDocument/formatting - (3)' in 35ms.
2024-10-15 15:07:03.570 [info] [Trace - 3:07:03 PM] Sending notification 'textDocument/didChange'.

[karthiknadig]

The extension just contributes a formatter. VS Code decides if it should be triggered on autosave or not. The issue here is that VS Code does not trigger formatting on autosave, it triggers it on explicit save.
see here microsoft/vscode#128090 (comment)