Make sure OnCallbackException is executed for AsyncConsumers

projects/RabbitMQ.Client/client/impl/AsyncConsumerWorkService.cs

@@ -94,6 +94,11 @@ private async Task Loop()
                             {
                                 await task.ConfigureAwait(false);
                             }
+                            else
+                            {
+                                // to materialize exceptions if any
+                                task.GetAwaiter().GetResult();
+                            }
                         }
                         catch (Exception e)
                         {
@@ -126,7 +131,7 @@ private async Task LoopWithConcurrency(CancellationToken cancellationToken)
                         while (_channel.Reader.TryRead(out Work work))
                         {
                             // Do a quick synchronous check before we resort to async/await with the state-machine overhead.
-                            if(!_limiter.Wait(0))
+                            if (!_limiter.Wait(0))
                             {
                                 await _limiter.WaitAsync(cancellationToken).ConfigureAwait(false);
                             }
@@ -150,6 +155,11 @@ private static async Task HandleConcurrent(Work work, IModel model, SemaphoreSli
                     {
                         await task.ConfigureAwait(false);
                     }
+                    else
+                    {
+                        // to materialize exceptions if any
+                        task.GetAwaiter().GetResult();
+                    }
                 }
                 catch (Exception e)
                 {

projects/Unit/TestAsyncConsumerExceptions.cs

@@ -0,0 +1,180 @@
+// This source code is dual-licensed under the Apache License, version
+// 2.0, and the Mozilla Public License, version 2.0.
+//
+// The APL v2.0:
+//
+//---------------------------------------------------------------------------
+//   Copyright (c) 2007-2020 VMware, Inc.
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//       https://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+//---------------------------------------------------------------------------
+//
+// The MPL v2.0:
+//
+//---------------------------------------------------------------------------
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+//
+//  Copyright (c) 2007-2020 VMware, Inc.  All rights reserved.
+//---------------------------------------------------------------------------
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using RabbitMQ.Client.Events;
+
+namespace RabbitMQ.Client.Unit
+{
+    [TestFixture]
+    public class TestAsyncConsumerExceptions : IntegrationFixture
+    {
+        private static Exception TestException = new Exception("oops");
+
+        protected void TestExceptionHandlingWith(IBasicConsumer consumer,
+            Action<IModel, string, IBasicConsumer, string> action)
+        {
+            var resetEvent = new AutoResetEvent(false);
+            bool notified = false;
+            string q = _model.QueueDeclare();
+
+            _model.CallbackException += (m, evt) =>
+            {
+                if (evt.Exception != TestException) return;
+
+                notified = true;
+                resetEvent.Set();
+            };
+
+            string tag = _model.BasicConsume(q, true, consumer);
+            action(_model, q, consumer, tag);
+            resetEvent.WaitOne();
+
+            Assert.IsTrue(notified);
+        }
+
+        [SetUp]
+        public override void Init()
+        {
+            _connFactory = new ConnectionFactory
+            {
+                DispatchConsumersAsync = true
+            };
+
+            _conn = _connFactory.CreateConnection();
+            _model = _conn.CreateModel();
+        }
+
+        [Test]
+        public void TestCancelNotificationExceptionHandling()
+        {
+            IBasicConsumer consumer = new ConsumerFailingOnCancel(_model);
+            TestExceptionHandlingWith(consumer, (m, q, c, ct) => m.QueueDelete(q));
+        }
+
+        [Test]
+        public void TestConsumerCancelOkExceptionHandling()
+        {
+            IBasicConsumer consumer = new ConsumerFailingOnCancelOk(_model);
+            TestExceptionHandlingWith(consumer, (m, q, c, ct) => m.BasicCancel(ct));
+        }
+
+        [Test]
+        public void TestConsumerConsumeOkExceptionHandling()
+        {
+            IBasicConsumer consumer = new ConsumerFailingOnConsumeOk(_model);
+            TestExceptionHandlingWith(consumer, (m, q, c, ct) => { });
+        }
+
+        [Test]
+        public void TestConsumerShutdownExceptionHandling()
+        {
+            IBasicConsumer consumer = new ConsumerFailingOnShutdown(_model);
+            TestExceptionHandlingWith(consumer, (m, q, c, ct) => m.Close());
+        }
+
+        [Test]
+        public void TestDeliveryExceptionHandling()
+        {
+            IBasicConsumer consumer = new ConsumerFailingOnDelivery(_model);
+            TestExceptionHandlingWith(consumer, (m, q, c, ct) => m.BasicPublish("", q, null, _encoding.GetBytes("msg")));
+        }
+
+        private class ConsumerFailingOnDelivery : AsyncEventingBasicConsumer
+        {
+            public ConsumerFailingOnDelivery(IModel model) : base(model)
+            {
+            }
+
+            public override Task HandleBasicDeliver(string consumerTag,
+                ulong deliveryTag,
+                bool redelivered,
+                string exchange,
+                string routingKey,
+                IBasicProperties properties,
+                ReadOnlyMemory<byte> body)
+            {
+                return Task.FromException(TestException);
+            }
+        }
+
+        private class ConsumerFailingOnCancel : AsyncEventingBasicConsumer
+        {
+            public ConsumerFailingOnCancel(IModel model) : base(model)
+            {
+            }
+
+            public override Task HandleBasicCancel(string consumerTag)
+            {
+                return Task.FromException(TestException);
+            }
+        }
+
+        private class ConsumerFailingOnShutdown : AsyncEventingBasicConsumer
+        {
+            public ConsumerFailingOnShutdown(IModel model) : base(model)
+            {
+            }
+
+            public override Task HandleModelShutdown(object model, ShutdownEventArgs reason)
+            {
+                return Task.FromException(TestException);
+            }
+        }
+
+        private class ConsumerFailingOnConsumeOk : AsyncEventingBasicConsumer
+        {
+            public ConsumerFailingOnConsumeOk(IModel model) : base(model)
+            {
+            }
+
+            public override Task HandleBasicConsumeOk(string consumerTag)
+            {
+                return Task.FromException(TestException);
+            }
+        }
+
+        private class ConsumerFailingOnCancelOk : AsyncEventingBasicConsumer
+        {
+            public ConsumerFailingOnCancelOk(IModel model) : base(model)
+            {
+            }
+
+            public override Task HandleBasicCancelOk(string consumerTag)
+            {
+                return Task.FromException(TestException);
+            }
+        }
+    }
+}