Handling exceptions thrown when invoking a hub method (#332)

src/Microsoft.AspNetCore.SignalR.Client/HubConnection.cs

@@ -102,8 +102,6 @@ namespace Microsoft.AspNetCore.SignalR.Client
         public Task<object> Invoke(string methodName, Type returnType, params object[] args) => Invoke(methodName, returnType, CancellationToken.None, args);
         public async Task<object> Invoke(string methodName, Type returnType, CancellationToken cancellationToken, params object[] args)
         {
-            // TODO: we should reject calls to here after the connection is "done" or has not been started (e.g. sending an invocation failed)
-
             _logger.LogTrace("Preparing invocation of '{0}', with return type '{1}' and {2} args", methodName, returnType.AssemblyQualifiedName, args.Length);
 
             // Create an invocation descriptor.
@@ -134,15 +132,26 @@ namespace Microsoft.AspNetCore.SignalR.Client
                 _logger.LogTrace("Invocation #{0}: {1} {2}({3})", descriptor.Id, returnType.FullName, methodName, argsList);
             }
 
-            var ms = new MemoryStream();
+            try
-            await _adapter.WriteMessageAsync(descriptor, ms, cancellationToken);
+            {
+                var ms = new MemoryStream();
+                await _adapter.WriteMessageAsync(descriptor, ms, cancellationToken);
 
-            _logger.LogInformation("Sending Invocation #{0}", descriptor.Id);
+                _logger.LogInformation("Sending Invocation #{0}", descriptor.Id);
 
-            // TODO: Format.Text - who, where and when decides about the format of outgoing messages
+                // TODO: Format.Text - who, where and when decides about the format of outgoing messages
-            // TODO HIGH: Handle return value/Exception from SendAsync
+                await _connection.SendAsync(ms.ToArray(), MessageType.Text, cancellationToken);
-            await _connection.SendAsync(ms.ToArray(), MessageType.Text, cancellationToken);
+                _logger.LogInformation("Sending Invocation #{0} complete", descriptor.Id);
-            _logger.LogInformation("Sending Invocation #{0} complete", descriptor.Id);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(0, ex, "Sending Invocation #{0} failed", descriptor.Id);
+                irq.Completion.TrySetException(ex);
+                lock (_pendingCallsLock)
+                {
+                    _pendingCalls.Remove(descriptor.Id);
+                }
+            }
 
             // Return the completion task. It will be completed by ReceiveMessages when the response is received.
             return await irq.Completion.Task;
@@ -294,7 +303,7 @@ namespace Microsoft.AspNetCore.SignalR.Client
 
             public InvocationRequest(CancellationToken cancellationToken, Type resultType)
             {
-                var tcs = new TaskCompletionSource<object>();
+                var tcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);
                 Completion = tcs;
                 CancellationToken = cancellationToken;
                 Registration = cancellationToken.Register(() => tcs.TrySetCanceled());

test/Microsoft.AspNetCore.SignalR.Client.Tests/HubConnectionTests.cs

@@ -13,6 +13,7 @@ using Microsoft.Extensions.Logging;
 using Moq;
 using Moq.Protected;
 using Xunit;
+using System.IO;
 
 namespace Microsoft.AspNetCore.SignalR.Client.Tests
 {
@@ -92,24 +93,43 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
             }
         }
 
-        [Fact(Skip = "Not implemented")]
+        [Fact]
         public async Task InvokeThrowsIfHubConnectionNotStarted()
         {
-            var hubConnection = new HubConnection(new Uri("http://fakeuri.org"), Mock.Of<IInvocationAdapter>(), Mock.Of<ILoggerFactory>());
+            var hubConnection = new HubConnection(new Uri("http://fakeuri.org"));
             var exception =
                 await Assert.ThrowsAsync<InvalidOperationException>(async () => await hubConnection.Invoke<int>("test"));
-            Assert.Equal("Cannot invoke methods on non-started connections.", exception.Message);
+            Assert.Equal("Cannot send messages when the connection is not in the Connected state.", exception.Message);
         }
 
-        [Fact(Skip = "Not implemented")]
+        [Fact]
         public async Task InvokeThrowsIfHubConnectionDisposed()
         {
-            var hubConnection = new HubConnection(new Uri("http://fakeuri.org"), Mock.Of<IInvocationAdapter>(), Mock.Of<ILoggerFactory>());
+            var hubConnection = new HubConnection(new Uri("http://fakeuri.org"));
             await hubConnection.DisposeAsync();
 
             var exception =
                 await Assert.ThrowsAsync<InvalidOperationException>(async () => await hubConnection.Invoke<int>("test"));
-                Assert.Equal("Cannot invoke methods on disposed connections.", exception.Message);
+                Assert.Equal("Cannot send messages when the connection is not in the Connected state.", exception.Message);
+        }
+
+        [Fact]
+        public async Task InvokeThrowsIfSerializingMessageFails()
+        {
+            var mockConnection = new Mock<IConnection>();
+
+            var exception = new InvalidOperationException();
+            var mockInvocationAdapter = new Mock<IInvocationAdapter>();
+            mockInvocationAdapter
+                .Setup(a => a.WriteMessageAsync(It.IsAny<InvocationMessage>(), It.IsAny<Stream>(), It.IsAny<CancellationToken>()))
+                .Returns(Task.FromException(exception));
+
+            var hubConnection = new HubConnection(mockConnection.Object, mockInvocationAdapter.Object, null);
+            await hubConnection.StartAsync(Mock.Of<ITransport>());
+
+            var actualException =
+                await Assert.ThrowsAsync<InvalidOperationException>(async () => await hubConnection.Invoke<int>("test"));
+            Assert.Same(exception, actualException);
         }
 
         [Fact]