Add support custom client hub method name (#23614)

Author: vahpetr

src/SignalR/server/Core/src/Internal/TypedClientBuilder.cs

@@ -144,6 +144,10 @@ private static void BuildMethod(TypeBuilder type, MethodInfo interfaceMethodInfo
                 paramTypes = paramTypes.Take(paramTypes.Length - 1).ToArray();
             }
 
+            var methodName =
+                    interfaceMethodInfo.GetCustomAttribute<HubMethodNameAttribute>()?.Name ??
+                    interfaceMethodInfo.Name;
+
             var generator = methodBuilder.GetILGenerator();
 
             // Declare local variable to store the arguments to IClientProxy.SendCoreAsync
@@ -154,7 +158,7 @@ private static void BuildMethod(TypeBuilder type, MethodInfo interfaceMethodInfo
             generator.Emit(OpCodes.Ldfld, proxyField);
 
             // The first argument to IClientProxy.SendCoreAsync is this method's name
-            generator.Emit(OpCodes.Ldstr, interfaceMethodInfo.Name);
+            generator.Emit(OpCodes.Ldstr, methodName);
 
             // Create an new object array to hold all the parameters to this method
             generator.Emit(OpCodes.Ldc_I4, paramTypes.Length); // Stack: 

src/SignalR/server/SignalR/test/Internal/TypedClientBuilderTests.cs

@@ -38,6 +38,30 @@ public async Task ProducesImplementationThatProxiesMethodsToIClientProxyAsync()
             await task.OrTimeout();
         }
 
+        [Fact]
+        public async Task ProducesImplementationThatProxiesMethodsToIRenamedClientProxyAsync()
+        {
+            var clientProxy = new MockProxy();
+            var typedProxy = TypedClientBuilder<IRenamedTestClient>.Build(clientProxy);
+
+            var objArg = new object();
+            var task = typedProxy.MethodAsync("foo", 42, objArg);
+            Assert.False(task.IsCompleted);
+
+            Assert.Collection(clientProxy.Sends,
+                send =>
+                {
+                    Assert.Equal("Method", send.Method);
+                    Assert.Equal("foo", send.Arguments[0]);
+                    Assert.Equal(42, send.Arguments[1]);
+                    Assert.Equal(CancellationToken.None, send.CancellationToken);
+                    Assert.Same(objArg, send.Arguments[2]);
+                    send.Complete();
+                });
+
+            await task.OrTimeout();
+        }
+
         [Fact]
         public async Task SupportsSubInterfaces()
         {
@@ -189,6 +213,12 @@ public interface ITestClient
             Task Method(string arg1, int arg2, object arg3);
         }
 
+        public interface IRenamedTestClient
+        {
+            [HubMethodName("Method")]
+            Task MethodAsync(string arg1, int arg2, object arg3);
+        }
+
         public interface IVoidMethodClient
         {
             void Method(string arg1, int arg2, object arg3);