(#109) TcpClientEx: add memory leak tests

SharpXMPP.NUnit/Compat/TcpClientExTests.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+using System.Threading.Tasks;
+using JetBrains.dotMemoryUnit;
+using NUnit.Framework;
+
+namespace SharpXMPP.Compat
+{
+    public class TcpClientExTests
+    {
+        private static int GetFreePort()
+        {
+            var host = new TcpListener(new IPEndPoint(IPAddress.Loopback, 0));
+            host.Start();
+            try
+            {
+                return ((IPEndPoint)host.LocalEndpoint).Port;
+            }
+            finally
+            {
+                host.Stop();
+            }
+        }
+
+        /// <summary>
+        /// This test checks for TcpClient leaks which are guaranteed to happen if the requests aren't properly
+        /// cancelled.
+        /// </summary>
+        /// <remarks>
+        /// Run with dotMemoryUnit to check for leaks, run without it for basic sanity check. For details see
+        /// https://www.jetbrains.com/help/dotmemory-unit/Get_Started.html#3-run-the-test
+        /// </remarks>
+        [Test, DotMemoryUnit(FailIfRunWithoutSupport = false)]
+        public void TestCancellation()
+        {
+            const int iterations = 100;
+            int cancelled = 0;
+
+            // Connecting to a free port takes enough time for the tasks to be cancelled in time.
+            var port = GetFreePort();
+            for (int i = 0; i < iterations; ++i)
+            {
+                Task.Run(async () =>
+                {
+                    using var cts = new CancellationTokenSource();
+                    var token = cts.Token;
+
+                    using var client = new TcpClient();
+                    var task = client.ConnectWithCancellationAsync(IPAddress.Loopback, port, token);
+                    cts.Cancel();
+
+                    try
+                    {
+                        await task;
+                    }
+                    catch (OperationCanceledException)
+                    {
+                        ++cancelled;
+                    }
+                }).Wait();
+            }
+
+            Assert.Greater(cancelled, 0);
+
+            dotMemory.Check(memory =>
+                // note there's 1 task object on pre-.NET 5 runtimes
+                Assert.LessOrEqual(memory.GetObjects(o => o.Type.Is<Task>()).ObjectsCount, 1));
+        }
+    }
+}

SharpXMPP.NUnit/SharpXMPP.NUnit.csproj

@@ -15,6 +15,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="JetBrains.DotMemoryUnit" Version="3.1.20200127.214830" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
     <PackageReference Include="NUnit" Version="3.13.2" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />

SharpXMPP.Shared/Compat/TcpClientEx.cs

@@ -20,6 +20,8 @@ private static async Task AbandonOnCancel(this Task task, CancellationToken canc
                     throw new OperationCanceledException(cancellationToken);
                 }
             }
+
+            await task;
         }
 #endif