Provide default implementation for IHubFilter.InvokeMethodAsync (#23968)

Author: BrennanConroy

src/SignalR/server/Core/src/IHubFilter.cs

@@ -19,7 +19,7 @@ public interface IHubFilter
         /// <param name="invocationContext">The context for the method invocation that holds all the important information about the invoke.</param>
         /// <param name="next">The next filter to run, and for the final one, the Hub invocation.</param>
         /// <returns>Returns the result of the Hub method invoke.</returns>
-        ValueTask<object> InvokeMethodAsync(HubInvocationContext invocationContext, Func<HubInvocationContext, ValueTask<object>> next);
+        ValueTask<object> InvokeMethodAsync(HubInvocationContext invocationContext, Func<HubInvocationContext, ValueTask<object>> next) => next(invocationContext);
 
         /// <summary>
         /// Allows handling of the <see cref="Hub.OnConnectedAsync"/> method.

src/SignalR/server/SignalR/test/HubFilterTests.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Diagnostics;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Internal;
 using Microsoft.Extensions.DependencyInjection;
@@ -136,6 +135,40 @@ private async Task AssertMethodsCalled(IServiceProvider serviceProvider, TcsServ
             }
         }
 
+        [Fact]
+        public async Task HubFilterDoesNotNeedToImplementMethods()
+        {
+            using (StartVerifiableLog())
+            {
+                var tcsService = new TcsService();
+                var serviceProvider = HubConnectionHandlerTestUtils.CreateServiceProvider(services =>
+                {
+                    services.AddSignalR().AddHubOptions<DynamicTestHub>(options =>
+                    {
+                        options.AddFilter(typeof(EmptyFilter));
+                    });
+                }, LoggerFactory);
+
+
+                var connectionHandler = serviceProvider.GetService<HubConnectionHandler<DynamicTestHub>>();
+
+                using (var client = new TestClient())
+                {
+                    var connectionHandlerTask = await client.ConnectAsync(connectionHandler);
+
+                    await client.Connected.OrTimeout();
+
+                    var completion = await client.InvokeAsync(nameof(DynamicTestHub.Echo), "hello");
+                    Assert.Null(completion.Error);
+                    Assert.Equal("hello", completion.Result);
+
+                    client.Dispose();
+
+                    await connectionHandlerTask.OrTimeout();
+                }
+            }
+        }
+
         [Fact]
         public async Task MutlipleFilters_MethodsAreCalled()
         {

src/SignalR/server/SignalR/test/TestFilters.cs

@@ -233,4 +233,9 @@ public ValueTask<object> InvokeMethodAsync(HubInvocationContext invocationContex
             return next(context);
         }
     }
+
+    public class EmptyFilter : IHubFilter
+    {
+        // Purposefully not implementing any methods
+    }
 }