From ad546adafe7b61a6182c4ff132f86893be3040db Mon Sep 17 00:00:00 2001
From: Christian <6939810+chkr1011@users.noreply.github.com>
Date: Wed, 3 Aug 2022 20:27:53 +0200
Subject: [PATCH] Fix removal of event handlers from async event.

---
 .github/workflows/ReleaseNotes.md             |  1 +
 MQTTnet.sln.DotSettings                       |  6 +-
 .../Internal/AsyncEvent_Tests.cs              | 66 +++++++++++++++++++
 .../MQTTnet/Internal/AsyncEventInvocator.cs   |  6 +-
 4 files changed, 74 insertions(+), 5 deletions(-)
 create mode 100644 Source/MQTTnet.Tests/Internal/AsyncEvent_Tests.cs

diff --git a/.github/workflows/ReleaseNotes.md b/.github/workflows/ReleaseNotes.md
index 883446ea..72eb8188 100644
--- a/.github/workflows/ReleaseNotes.md
+++ b/.github/workflows/ReleaseNotes.md
@@ -1,3 +1,4 @@
+* [Core] Fixed not working removal of event handlers from async events (#1479).
 * [Client] Added support for passing the local endpoint (network card) which should be used (#1311).
 * [Client] Exposed _PackageIdentifier_ in _MqttApplicationMessageReceivedEventArgs_ (thanks to @koepalex, #1466).
 * [Server] Added a new event (_ClientAcknowledgedPublishPacketAsync_) which is fired whenever a client acknowledges a PUBLISH packet (QoS 1 and 2, #487).
diff --git a/MQTTnet.sln.DotSettings b/MQTTnet.sln.DotSettings
index 87d205d0..dfaffacc 100644
--- a/MQTTnet.sln.DotSettings
+++ b/MQTTnet.sln.DotSettings
@@ -226,9 +226,9 @@
     &lt;/Entry&gt;
   &lt;/TypePattern&gt;
 &lt;/Patterns&gt;</s:String>
-	<s:String x:Key="/Default/CodeStyle/FileHeader/FileHeaderText/@EntryValue">// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.</s:String>
+	<s:String x:Key="/Default/CodeStyle/FileHeader/FileHeaderText/@EntryValue">Licensed to the .NET Foundation under one or more agreements.
+The .NET Foundation licenses this file to you under the MIT license.
+See the LICENSE file in the project root for more information.</s:String>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpAttributeForSingleLineMethodUpgrade/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpKeepExistingMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpPlaceEmbeddedOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>
diff --git a/Source/MQTTnet.Tests/Internal/AsyncEvent_Tests.cs b/Source/MQTTnet.Tests/Internal/AsyncEvent_Tests.cs
new file mode 100644
index 00000000..3c1fdc90
--- /dev/null
+++ b/Source/MQTTnet.Tests/Internal/AsyncEvent_Tests.cs
@@ -0,0 +1,66 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Implementations;
+using MQTTnet.Internal;
+
+namespace MQTTnet.Tests.Internal
+{
+    [TestClass]
+    public sealed class AsyncEvent_Tests
+    {
+        int _testEventAsyncCount;
+
+        [TestMethod]
+        public async Task Attach_EventHandler()
+        {
+            var testClass = new TestClass();
+
+            testClass.TestEventAsync += OnTestEventAsync;
+
+            await testClass.FireEventAsync(EventArgs.Empty);
+
+            Assert.AreEqual(1, _testEventAsyncCount);
+        }
+
+        [TestMethod]
+        public async Task Detach_EventHandler()
+        {
+            var testClass = new TestClass();
+
+            testClass.TestEventAsync += OnTestEventAsync;
+            testClass.TestEventAsync -= OnTestEventAsync;
+
+            await testClass.FireEventAsync(EventArgs.Empty);
+
+            Assert.AreEqual(0, _testEventAsyncCount);
+        }
+
+        Task OnTestEventAsync(EventArgs arg)
+        {
+            Interlocked.Increment(ref _testEventAsyncCount);
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
+        sealed class TestClass
+        {
+            readonly AsyncEvent<EventArgs> _testEvent = new AsyncEvent<EventArgs>();
+
+            public event Func<EventArgs, Task> TestEventAsync
+            {
+                add => _testEvent.AddHandler(value);
+                remove => _testEvent.RemoveHandler(value);
+            }
+
+            public Task FireEventAsync(EventArgs eventArgs)
+            {
+                return _testEvent.InvokeAsync(eventArgs);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Source/MQTTnet/Internal/AsyncEventInvocator.cs b/Source/MQTTnet/Internal/AsyncEventInvocator.cs
index 55541837..6258b28b 100644
--- a/Source/MQTTnet/Internal/AsyncEventInvocator.cs
+++ b/Source/MQTTnet/Internal/AsyncEventInvocator.cs
@@ -21,12 +21,14 @@ namespace MQTTnet.Internal
 
         public bool WrapsHandler(Action<TEventArgs> handler)
         {
-            return ReferenceEquals(_handler, handler);
+            // Do not use ReferenceEquals! It will not work with delegates.
+            return handler == _handler;
         }
         
         public bool WrapsHandler(Func<TEventArgs, Task> handler)
         {
-            return ReferenceEquals(_asyncHandler, handler);
+            // Do not use ReferenceEquals! It will not work with delegates.
+            return handler == _asyncHandler;
         }
         
         public Task InvokeAsync(TEventArgs eventArgs)