I managed to get some tests running in a WinRT application context without too much trouble, I think it would be better to run the tests with it if we intend to check how it is supposed to work.
Impressive, very nice. I had no doubt you could get the tests running.
I'm not sure how you did it but in my VM I tried adding an AppxManifest.xml file with <Application> tag including the executable attribute along with the test in the same folder and ran the PowerShell command `Add-AppxPackage`. After tinkering with it, I managed to get it to install the app but not the exe with it. Even using the MSIX Packaging Tool did not help.
I'd suggest to split the IDL changes to a separate MR in the meantime, and I'll work on getting some framework available upstream to run the tests.
Sounds good, MR https://gitlab.winehq.org/wine/wine/-/merge_requests/3552 created.