CustomHost Launch Timeout fix

src/Microsoft.TestPlatform.Client/DesignMode/DesignModeClient.cs

@@ -23,7 +23,7 @@ public class DesignModeClient : IDesignModeClient
 
         private readonly IDataSerializer dataSerializer;
 
-        private Action<Message> onAckMessageReceived;
+        protected Action<Message> onAckMessageReceived;
 
         private object ackLockObject = new object();
 
@@ -178,11 +178,13 @@ private void ProcessRequests(ITestRequestManager testRequestManager)
                                 testRequestManager.AbortTestRun();
                                 break;
                             }
+
                         case MessageType.CustomTestHostLaunchCallback:
                             {
                                 this.onAckMessageReceived?.Invoke(message);
                                 break;
                             }
+
                         case MessageType.SessionEnd:
                             {
                                 EqtTrace.Info("DesignModeClient: Session End message received from server. Closing the connection.");
@@ -227,9 +229,15 @@ public int LaunchCustomHost(TestProcessStartInfo testProcessStartInfo)
                 };
 
                 this.communicationManager.SendMessage(MessageType.CustomTestHostLaunch, testProcessStartInfo);
-                waitHandle.WaitOne(ClientListenTimeOut);
 
+                // LifeCycle of the TP through DesignModeClient is maintained by the IDEs or user-facing-clients like LUTs, who call TestPlatform
+                // TP is handing over the control of launch to these IDEs and so, TP has to wait indefinite
+                // Even if TP has a timeout here, there is no way TP can abort or stop the thread/task that is hung in IDE or LUT
+                // Even if TP can abort the API somehow, TP is essentially putting IDEs or Clients in inconsistent state without having info on
+                // Since the IDEs own user-UI-experience here, TP will let the custom host launch as much time as IDEs define it for their users
+                waitHandle.WaitOne();
                 this.onAckMessageReceived = null;
+
                 return this.dataSerializer.DeserializePayload<int>(ackMessage);
             }
         }

test/Microsoft.TestPlatform.Client.UnitTests/DesignMode/DesignModeClientTests.cs

@@ -19,6 +19,7 @@ namespace Microsoft.VisualStudio.TestPlatform.Client.UnitTests.DesignMode
     using Moq;
 
     using Newtonsoft.Json.Linq;
+    using System.Threading.Tasks;
 
     [TestClass]
     public class DesignModeClientTests
@@ -222,5 +223,42 @@ public void DesignModeClientShouldStopCommunicationOnParentProcessExit()
 
             this.mockCommunicationManager.Verify(cm => cm.StopClient(), Times.Once);
         }
+
+        [TestMethod]
+        public void DesignModeClientLaunchCustomHostMustReturnIfAckComes()
+        {
+            var testableDesignModeClient = new TestableDesignModeClient(this.mockCommunicationManager.Object, JsonDataSerializer.Instance);
+
+            this.mockCommunicationManager.Setup(cm => cm.WaitForServerConnection(It.IsAny<int>())).Returns(true);
+
+            var expectedProcessId = 1234;
+            Action sendMessageAction = () =>
+            {
+                testableDesignModeClient.InvokeCustomHostLaunchAckCallback(expectedProcessId);
+            };
+
+            this.mockCommunicationManager.Setup(cm => cm.SendMessage(MessageType.CustomTestHostLaunch, It.IsAny<object>())).
+                Callback(() => Task.Run(sendMessageAction));
+
+            var info = new TestProcessStartInfo();
+            var processId = testableDesignModeClient.LaunchCustomHost(info);
+
+            Assert.AreEqual(expectedProcessId, processId);
+        }
+
+        private class TestableDesignModeClient : DesignModeClient
+        {
+            internal TestableDesignModeClient(ICommunicationManager communicationManager, 
+                IDataSerializer dataSerializer)
+                : base(communicationManager, dataSerializer)
+            {
+            }
+
+            public void InvokeCustomHostLaunchAckCallback(int processId)
+            {
+                this.onAckMessageReceived?.Invoke(
+                    new Message() { MessageType = MessageType.CustomTestHostLaunchCallback, Payload = JToken.FromObject(processId) });
+            }
+        }
     }
 }