SignalR testing - how to mock groups in new version of SignalR for ASP.NET Core 2

Question

I try to write test for my Hub method, but I don't know as because there is no documentation or code examples for current (1.0.0-alpha2-final) version of SignalR. There is my code:

[Fact]
public void SaveVisitorInfoTest()
{   
    //Arrange
    var chatHub = new ChatHub();
    var mockClients = new Mock<IHubClients>();
    chatHub.Clients = mockClients.Object;
    dynamic groups = new ExpandoObject();
    var groupName = "SomeConversation";
    string actualName = null;
    string expectedName = "someName";
    groups.SendVisitorInfo = new Action<string, string>(n => {
        actualName = n;
    });
    mockClients.Setup(_ => _.Group(groupName)).Returns(groups);

    //Act
    chatHub.Clients.Group(groupName).InvokeAsync("SendVisitorInfo", expectedName);

    // Assert
    Assert.Equal(expectedName, actualName);
}

Visual Studio generates next error message while running the test:

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException : 'Moq.Language.Flow.ISetup' does not contain a definition for 'Returns'

In old versions mock clients and groups creation looks like this:

var mockClients = new Mock<IHubCallerConnectionContext<dynamic>>();
dynamic groups = new ExpandoObject();
groups.SendVisitorInfo = new Action<string, string>(n => {
        actualName = n;
    });
mockClients.Setup(_ => _.Group(groupName)).Returns((ExpandoObject)groups)

But I can't use IHubCallerConnectionContext now, so I tried:

var mockClients = new Mock<IHubClients>();

but i don't know how to create mock groups in this case

Sorry for my terrible english

Answer 1

I don't have enough rep to comment but this link was as good as I could find for testing AspNetCore.SignalR v1.0.2:

https://buildingsteps.wordpress.com/2018/06/12/testing-signalr-hubs-in-asp-net-core-2-1/

It's still pretty ugly.

What I want to be able to do is

public Task DoCallback(IHubContext<MyHub> hubContext)
{
   var clients = m_hubContext.Clients as IHubClients<IMyHubClient>;
   clients.Client( "one").myCallback("Hi!");
}

Then mock out like:

var hubContext = new Mock<IHubContext<MyHub>>();
hubContext.Setup( h => h.Clients )
          .Returns( m_hubClients.Object );

var hubClients = new Mock<IHubClients>();

var clientCallbacks = new Mock<IMyHubClient>();

hubClients.As<IHubClients<IMyHubClient>>()
          .Setup( c => c.Client( "one" ) )
          .Returns( clientCallbacks.Object );

clientCallbacks.Setup( c => c.myCallback( It.IsAny<string>() ) )
               .Callback( ( stringp ) =>
              {
...etc...

Hopefully in a future release...