Capture gRPC interop test client output

src/Grpc/test/InteropTests/Helpers/ClientProcess.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Internal;
@@ -15,9 +16,13 @@ public class ClientProcess : IDisposable
         private readonly Process _process;
         private readonly ProcessEx _processEx;
         private readonly TaskCompletionSource<object> _startTcs;
+        private readonly StringBuilder _output;
+        private readonly object _outputLock = new object();
 
         public ClientProcess(ITestOutputHelper output, string path, string serverPort, string testCase)
         {
+            _output = new StringBuilder();
+
             _process = new Process();
             _process.StartInfo = new ProcessStartInfo
             {
@@ -28,21 +33,26 @@ public ClientProcess(ITestOutputHelper output, string path, string serverPort, s
             };
             _process.EnableRaisingEvents = true;
             _process.OutputDataReceived += Process_OutputDataReceived;
+            _process.ErrorDataReceived += Process_ErrorDataReceived;
             _process.Start();
 
             _processEx = new ProcessEx(output, _process, timeout: Timeout.InfiniteTimeSpan);
 
             _startTcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);
         }
 
-        public Task WaitForReady()
+        public Task WaitForReadyAsync() => _startTcs.Task;
+        public Task WaitForExitAsync() => _processEx.Exited;
+        public int ExitCode => _process.ExitCode;
+
+        public string GetOutput()
         {
-            return _startTcs.Task;
+            lock (_outputLock)
+            {
+                return _output.ToString();
+            }
         }
 
-        public int ExitCode => _process.ExitCode;
-        public Task Exited => _processEx.Exited;
-
         private void Process_OutputDataReceived(object sender, DataReceivedEventArgs e)
         {
             var data = e.Data;
@@ -52,6 +62,23 @@ private void Process_OutputDataReceived(object sender, DataReceivedEventArgs e)
                 {
                     _startTcs.TrySetResult(null);
                 }
+
+                lock (_outputLock)
+                {
+                    _output.AppendLine(data);
+                }
+            }
+        }
+
+        private void Process_ErrorDataReceived(object sender, DataReceivedEventArgs e)
+        {
+            var data = e.Data;
+            if (data != null)
+            {
+                lock (_outputLock)
+                {
+                    _output.AppendLine(data);
+                }
             }
         }
 

src/Grpc/test/InteropTests/InteropTests.cs

@@ -2,9 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Threading.Tasks;
 using InteropTests.Helpers;
 using Microsoft.AspNetCore.Testing;
@@ -36,11 +34,22 @@ public async Task InteropTestCase(string name)
 
                 using (var clientProcess = new ClientProcess(_output, _clientPath, serverProcess.ServerPort, name))
                 {
-                    await clientProcess.WaitForReady().TimeoutAfter(DefaultTimeout);
+                    try
+                    {
+                        await clientProcess.WaitForReadyAsync().TimeoutAfter(DefaultTimeout);
 
-                    await clientProcess.Exited.TimeoutAfter(DefaultTimeout);
+                        await clientProcess.WaitForExitAsync().TimeoutAfter(DefaultTimeout);
 
-                    Assert.Equal(0, clientProcess.ExitCode);
+                        Assert.Equal(0, clientProcess.ExitCode);
+                    }
+                    catch (Exception ex)
+                    {
+                        var clientOutput = clientProcess.GetOutput();
+                        var errorMessage = $@"Error while running client process. Process output:
+======================================
+{clientOutput}";
+                        throw new InvalidOperationException(errorMessage, ex);
+                    }
                 }
             }
         }