Add SignalR Marker Service (#1573)

src/Microsoft.AspNetCore.SignalR/SignalRAppBuilderExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace Microsoft.AspNetCore.Builder
 {
@@ -10,6 +11,13 @@ namespace Microsoft.AspNetCore.Builder
     {
         public static IApplicationBuilder UseSignalR(this IApplicationBuilder app, Action<HubRouteBuilder> configure)
         {
+            var marker = app.ApplicationServices.GetService(typeof(SignalRMarkerService));
+            if (marker == null)
+            {
+                throw new InvalidOperationException("Unable to find the SignalR service. Please add it by " +
+                    "calling 'IServiceCollection.AddSignalR()'.");
+            }
+
             app.UseSockets(routes =>
             {
                 configure(new HubRouteBuilder(routes));

src/Microsoft.AspNetCore.SignalR/SignalRDependencyInjectionExtensions.cs

@@ -12,6 +12,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public static ISignalRBuilder AddSignalR(this IServiceCollection services)
         {
             services.AddSockets();
+            services.AddSingleton<SignalRMarkerService>();
             services.AddSingleton<IConfigureOptions<HubOptions>, HubOptionsSetup>();
             return services.AddSignalRCore()
                 .AddJsonProtocol();

src/Microsoft.AspNetCore.SignalR/SignalRMarkerService.cs

@@ -0,0 +1,9 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    internal class SignalRMarkerService
+    {
+    }
+}

test/Microsoft.AspNetCore.SignalR.Tests/MapSignalRTests.cs

@@ -23,6 +23,26 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             Assert.Equal("Duplicate definitions of 'OverloadedMethod'. Overloading is not supported.", ex.Message);
         }
 
+        [Fact]
+        public void NotAddingSignalRServiceThrows()
+        {
+            var t = new WebHostBuilder()
+            .UseKestrel()
+            .Configure(app =>
+            {
+                var ex = Assert.Throws<InvalidOperationException>(() => {
+                    app.UseSignalR(options =>
+                    {
+                        options.MapHub<AuthHub>("/overloads");
+                    });
+                });
+
+                Assert.Equal("Unable to find the SignalR service. Please add it by calling 'IServiceCollection.AddSignalR()'.", ex.Message);
+            })
+            .Build();
+
+        }
+
         [Fact]
         public void MapHubFindsAuthAttributeOnHub()
         {