We have tests for the 3rd-party integration, but they're not run automatically.
Also when they're run manually, they fail.
We should clarify whether we can run them automatically. The reason why we dropped the automated tests was that we switched everything (DAVx5 + synctools) from a 3rd-party Github CI action to the official way of GMD. And as far as I know, there's no way to install an APK to a GMD before running the tests (yes it sounds a bit unbelievable).