Show detailed error message for HubExceptions (#2461)

src/Microsoft.AspNetCore.SignalR.Core/Internal/ErrorMessageHelper.cs

@@ -9,12 +9,13 @@ namespace Microsoft.AspNetCore.SignalR.Internal
     {
         internal static string BuildErrorMessage(string message, Exception exception, bool includeExceptionDetails)
         {
-            if (!includeExceptionDetails)
+            if (exception is HubException || includeExceptionDetails)
             {
-                return message;
+                return $"{message} {exception.GetType().Name}: {exception.Message}";
+
             }
 
-            return message + $" {exception.GetType().Name}: {exception.Message}";
+            return message;
         }
     }
 }

test/Microsoft.AspNetCore.SignalR.Tests/HubConnectionHandlerTestUtils/Hubs.cs

@@ -121,6 +121,11 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             throw new InvalidOperationException("BOOM!");
         }
 
+        public void ThrowHubException()
+        {
+            throw new HubException("This is a hub exception");
+        }
+
         public Task MethodThatYieldsFailedTask()
         {
             return Task.FromException(new InvalidOperationException("BOOM!"));

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

@@ -540,6 +540,30 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             }
         }
 
+        [Fact]
+        public async Task DetailedExceptionEvenWhenNotExplicitlySet()
+        {
+            var serviceProvider = HubConnectionHandlerTestUtils.CreateServiceProvider();
+
+            var methodName = nameof(MethodHub.ThrowHubException);
+
+            var connectionHandler = serviceProvider.GetService<HubConnectionHandler<MethodHub>>();
+
+            using (var client = new TestClient())
+            {
+                var connectionHandlerTask = await client.ConnectAsync(connectionHandler);
+
+                var message = await client.InvokeAsync(methodName).OrTimeout();
+
+                Assert.Equal($"An unexpected error occurred invoking '{methodName}' on the server. HubException: This is a hub exception", message.Error);
+
+                // kill the connection
+                client.Dispose();
+
+                await connectionHandlerTask.OrTimeout();
+            }
+        }
+
         [Fact]
         public async Task HubMethodDoesNotSendResultWhenInvocationIsNonBlocking()
         {