Has anyone mocked signalR client connection - HubConnection class?

[dcs3spp]

I am a new user to bUnit and have managed to get some tests running for NavMenu to grasp the basic concepts.
However, a different Blazor page makes a request to a signalR hub for communication of workflow state.

How to mock signalR connection?

Server Page that uses an additional signalR connection to communicate workflow state

 protected override async Task OnAfterRenderAsync(bool firstRender)
        {
            if (firstRender)
            {
                var hubUrl = NavigationManager.BaseUri.TrimEnd('/') + "/motionhub";

                try
                {
                    Logger.LogInformation("Index.razor page is performing initial render, connecting to secondary signalR hub");

                    hubConnection = new HubConnectionBuilder()
                        .WithUrl(hubUrl)
                        .ConfigureLogging(logging =>
                        {
                            logging.AddConsole();
                            logging.AddFilter("Microsoft.AspNetCore.SignalR", LogLevel.Information);
                        })
                        .AddJsonProtocol(options =>
                        {
                            options.PayloadSerializerOptions = JsonConvertersFactory.CreateDefaultJsonConverters(LoggerMotionDetection, LoggerMotionInfo, LoggerJsonVisitor);
                        })
                        .Build();

                    hubConnection.On<MotionDetection>("ReceiveMotionDetection", ReceiveMessage);
                    hubConnection.Closed += CloseHandler;

                    Logger.LogInformation("Starting HubConnection");
                    await hubConnection.StartAsync();
                    Logger.LogInformation("Index Razor Page initialised, listening on signalR hub => " + hubUrl.ToString());
                }
                catch (Exception e)
                {
                    Logger.LogError(e, "Encountered exception => " + e);
                }
            }
        }

Stub Unit Test Class

 public class IndexTest : TestContext, IDisposable
    {
        private MotionDetectionRepository repo;

        public IndexTest()
        {
            var mock = new Mock<IMotionDetectionSerializer<MotionDetection>>();
            repo = new MotionDetectionRepository(mock.Object, new NullLogger<MotionDetectionRepository>());

            Services.AddScoped<ILogger<MotionDetectionRepository>, NullLogger<MotionDetectionRepository>>();
            Services.AddScoped<ILogger<MotionInfoConverter>, NullLogger<MotionInfoConverter>>();
            Services.AddScoped<ILogger<MotionDetectionConverter>, NullLogger<MotionDetectionConverter>>();
            Services.AddScoped<ILogger<JsonVisitor>, NullLogger<JsonVisitor>>();
            Services.AddScoped<ILogger<WebApp.Pages.Index>, NullLogger<WebApp.Pages.Index>>();
            Services.AddScoped<IMotionDetectionRepository>(sp => repo);
            Services.AddScoped<MockNavigationManager>();
            Services.AddSignalR();
        }

        [Fact]
        public void Test()
        {
            var cut = RenderComponent<WebApp.Pages.Index>();

            Console.WriteLine($"{cut.Markup}");
        }
    }

[dcs3spp]

After reading:

• HubConnection interface dotnet/aspnetcore#14924
• Need example on stubbing client HubConnection  dotnet/aspnetcore#8133

The official stance from Microsoft is to implement a wrapper interface and use that. Looks like this has been done here so going to use that as a strating point.

Hope this helps others.

[egil]

That would be my recommendation as well. As soon as you are "new-ing" something up in a component/system under test, then mocking is usually close to impossible.

[dcs3spp]

Many thanks @egil. Yes, I am now in process of refactoring OnAfterRenderAsync in SUT listed above, to inject a factory dependency for creating wrapper interface...