In Windows, the pairing is already designed to be "Just Works" without any user interaction:
https://github.com/hbldh/bleak/blob/develop/bleak/backends/winrt/client.py#L367-L368

A pairing request is sent and the method in the link above should just accept the pairing without any further processing needed.

If a dialog is brought up, then that is a change in how Windows handles pairing. I did not get a dialog when I paired the last time.

From the Microsoft UWP docs concering the ConfirmOnly solution:

The application must confirm they wish to perform the pairing action. You can present an optional confirmation dialog to the user. With a value of ConfirmOnly, call Accept from the event args of the PairingRequested event handler if you want the pairing to complete.

For integration tests, just monkeypatch the pair function on the client to this

async def mock_pair_success(client, protection_level: int = None, **kwargs) -> bool:
    return True

client.pair = mock_pair_success

You will never be able to test pairing without performing the actual pairing with Bleak, since it uses the OS native BLE APIs. You could possible monkeypatch the CustomPairing class from the winrt package, but I do not think you will gain anything by doing that...

If a dialog is brought up, then that is a change in how Windows handles pairing. I did not get a dialog when I paired the last time.

using Windows version 10.0.19042 Build 19042. it's not latest and greatest

You will never be able to test pairing without performing the actual pairing with Bleak, since it uses the OS native BLE APIs. You could possible monkeypatch the CustomPairing class from the winrt package, but I do not think you will gain anything by doing that...

I don't want to prevent pairing at all I just want to do it in a way that I don't need to process any user dialog. just processing it in code or automatically if possible.

should just works (like you describe for windows above) also work in a linux environment?

This is not technically possible on macOS. For Windows and Linux, there is a pull request open for this, but it has been stalled. #640

This is not technically possible on macOS. For Windows and Linux, there is a pull request open for this, but it has been stalled. #640

This is a problem for my team's work in MacOS 12+ right now. :(