单元测试 Microsoft Band

Question

Trying to do unit testing using MSTest in VS2015 with the Microsoft Band nuGet package and running into the following error

"Microsoft.Band.BandIOException: An error occurred while attempting to acquire the Bluetooth device service.
This error can occur if the paired device is unreachable or has become unpaired from the current host. 
System.InvalidOperationException: A method was called at an unexpected time. (Exception from HRESULT: 0x8000000E)".

Code runs fine when run inside the application. It fails on the line to call BandClientManager.Instance.ConnectAsync .

Answer 1

The exception and error message are not helpful here, but you must establish Bluetooth connections on a UI thread. This is because the app might prompt the user and ask if they want to allow access to the Bluetooth device.

For example, in a UWP app, you can do the following to ensure UI thread execution:

await Windows.ApplicationModel.Core.CoreApplication.MainView.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, async () =>
{
    IBandClient client = await BandClientManager.Instance.ConnectAsync(...);
    ...
});

Alternatively, if you have access to a UI control, you can use its Dispatcher directly.

Any code that ultimately calls BluetoothLEDevice.FromBluetoothAddressAsync must do it on a UI thread. The Bluetooth access prompt will happen whenever the app package manifest ( .appxmanifest ) changes.

I can't imagine this fix being dependable for unit tests since there's no UI. I'm not sure what the intended fix is besides mocking the client interfaces and just avoiding Bluetooth altogether.