Fix race condition on testhost exit before we connect

src/Microsoft.TestPlatform.CrossPlatEngine/Client/ProxyOperationManager.cs

@@ -167,6 +167,7 @@ public virtual bool SetupChannel(IEnumerable<string> sources, string runSettings
                 if (!this.testHostLaunched ||
                     !this.RequestSender.WaitForRequestHandlerConnection(connTimeout * 1000, this.CancellationTokenSource.Token))
                 {
+                    EqtTrace.Verbose($"Test host failed to start Test host launched:{testHostLaunched} test host exited: {testHostExited.IsSet}");
                     // Throw a test platform exception with the appropriate message if user requested cancellation
                     this.CancellationTokenSource.Token.ThrowTestPlatformExceptionIfCancellationRequested();
 
@@ -209,7 +210,9 @@ public virtual void Close()
 
                     // We want to give test host a chance to safely close.
                     // The upper bound for wait should be 100ms.
-                    this.testHostExited.Wait(100);
+                    var timeout = 100;
+                    EqtTrace.Verbose("ProxyOperationManager.Close: waiting for test host to exit for {0} ms", timeout);
+                    this.testHostExited.Wait(timeout);
                 }
             }
             catch (Exception ex)
@@ -315,16 +318,24 @@ private void TestHostManagerHostLaunched(object sender, HostProviderEventArgs e)
 
         private void TestHostManagerHostExited(object sender, HostProviderEventArgs e)
         {
+            EqtTrace.Verbose("CrossPlatEngine.TestHostManagerHostExited: calling on client process exit callback.");
             this.testHostProcessStdError = e.Data;
-            this.RequestSender.OnClientProcessExit(this.testHostProcessStdError);
 
+            // this needs to be set before we call the OnClientProcess exit
+            // because the OnClientProcess will short-circuit WaitForRequestHandlerConnection in SetupChannel
+            // that then continues to throw an exception and checks if the testhost process exited
+            // if not it reports timeout, if we don't set this before OnClientProcessExit we will report timeout
+            // even though we exited the test host before even attempting the connect
             this.testHostExited.Set();
+            this.RequestSender.OnClientProcessExit(this.testHostProcessStdError);
         }
 
         private void ThrowOnTestHostExited(bool testHostExited)
-        {
+        {            
             if (testHostExited)
             {
+                // we might consider passing standard output here in case standard error is not available because some 
+                // errors don't end up in the standard error output
                 throw new TestPlatformException(string.Format(CrossPlatEngineResources.TestHostExitedWithError, this.testHostProcessStdError));
             }
         }

src/Microsoft.TestPlatform.TestHostProvider/Hosting/DotnetTestHostManager.cs

@@ -376,8 +376,13 @@ private void OnHostExited(HostProviderEventArgs e)
             if (!this.hostExitedEventRaised)
             {
                 this.hostExitedEventRaised = true;
+                EqtTrace.Verbose("DotnetTestHostManager.OnHostExited: invoking OnHostExited callback");
                 this.HostExited.SafeInvoke(this, e, "HostProviderEvents.OnHostExited");
             }
+            else
+            {
+                EqtTrace.Verbose("DotnetTestHostManager.OnHostExited: exit event was already raised, skipping");
+            }
         }
 
         private bool LaunchHost(TestProcessStartInfo testHostStartInfo, CancellationToken cancellationToken)

src/Microsoft.TestPlatform.TestHostProvider/Hosting/TestHostManagerCallbacks.cs

@@ -28,6 +28,7 @@ public static void ExitCallBack(
             StringBuilder testHostProcessStdError,
             Action<HostProviderEventArgs> onHostExited)
         {
+            EqtTrace.Verbose("TestHostProvider.ExitCallBack: Host exited starting callback.");
             var exitCode = 0;
             var testHostProcessStdErrorStr = testHostProcessStdError.ToString();
 
@@ -38,8 +39,9 @@ public static void ExitCallBack(
             {
                 procId = (process as Process).Id;
             }
-            catch (InvalidOperationException)
+            catch (InvalidOperationException ex)
             {
+                EqtTrace.Error("TestHostProvider.ExitCallBack: could not get proccess id from process, error: {0}.", ex);
             }
 
             if (exitCode != 0)