Agfdhyk

I have a method I need to Unittest and I am stuck with mocking part of it.

private async void LoginCommandAsync()

    {



        .....



        CancellationToken ct;

        var result = await ClientAuthorizationService.CurrentClient.InvokeApiAsync(Constants.ApiConstants.AzureAuthMeData,

            null, HttpMethod.Get, null, ct);



        ....

    }

I tried to mock the Microsoft.WindowsAzure.MobileServices.MobileServiceClient using Moq. Unfortunatly I always get a System.InvalidCastException in the last code line

        var currentClient = new Mock<IMobileServiceClient>(MockBehavior.Loose);



        currentClient.Setup(x => x.InvokeApiAsync(Constants.ApiConstants.AzureAuthMeData,

            null, HttpMethod.Get, null, ct)).Returns(Task.FromResult(token));



        var disposableCurrentClient = currentClient.As<IDisposable>();



        ClientAuthorizationService.CurrentClient = (MobileServiceClient)disposableCurrentClient.Object;

MobileServiceClient inherits from IMobileServiceClient, IDisposable but no matter how I try to use/assign the mocked object... it does not work.

public class ClientAuthorizationService : IClientAuthorizationService

{

    public MobileServiceClient CurrentClient { get; set; }

    public ClientAuthorizationService()

    {

        CurrentClient = new MobileServiceClient(Constants.ApiConstants.ApplicationUrl);

    }

} 

Change ClientAuthorizationService.CurrentClient member/property from MobileServiceClient to IMobileServiceClient

public interface IClientAuthorizationService  {

    IMobileServiceClient CurrentClient { get; set; }

}



public class ClientAuthorizationService : IClientAuthorizationService {



    public ClientAuthorizationService() {

        CurrentClient = new MobileServiceClient(Constants.ApiConstants.ApplicationUrl);

    }



    public IMobileServiceClient CurrentClient { get; set; }

} 

This will allow for a mock of the client to be assigned when testing as ClientAuthorizationService is now dependent on abstractions and not implementation concerns.

//....



var clientAuthorizationService = new Mock<IClientAuthorizationService>();



var currentClient = new Mock<IMobileServiceClient>();



currentClient

    .Setup(_ => _.InvokeApiAsync(It.IsAny<string>(), null, HttpMethod.Get, null, It.IsAny<CancellationToken>()))

    .ReturnsAsync(token);



clientAuthorizationService

    .Setup(_ => _.CurrentClient)

    .Returns(currentClient.Object);



//.....

Also it is advised not to use async void except for event handlers

So the code under test needs to be updated accordingly.

private async Task LoginCommandAsync() {



    //.....



    CancellationToken ct;

    var result = await ClientAuthorizationService.CurrentClient.InvokeApiAsync(Constants.ApiConstants.AzureAuthMeData,

        null, HttpMethod.Get, null, ct);



    //....

}