Used a changing pipe name

This ensures that we can have multiple worker processes running at the
same time.

xunit.runner.data/Constants.cs

@@ -8,9 +8,6 @@ namespace xunit.runner.data
 {
     public static class Constants
     {
-        // TODO: In order to support multiple runs this can't be a fixed name.  Needs to be a prefix that increments
-        // with every run to keep it unique.
-        public const string PipeName = "xunit.runners.pipe";
         public const string ActionDiscover = "discover";
         public const string ActionRun = "run";
         public static readonly Encoding Encoding = Encoding.UTF8;

xunit.runner.worker/Program.cs

@@ -16,26 +16,28 @@ namespace xunit.runner.worker
 
         public static int Main(string[] args)
         {
-            if (args.Length < 2)
+            if (args.Length < 3)
             {
                 Usage();
                 return ExitError;
             }
 
+            string pipeName = args[0];
+            string action = args[1];
+            string argument = args[2];
+
             Stream stream = null;
             try
             {
-                var namedPipeServerStream = new NamedPipeServerStream(Constants.PipeName);
-                namedPipeServerStream.WaitForConnection();
-                stream = namedPipeServerStream;
+                stream = CreateStream(pipeName);
 
-                switch (args[0])
+                switch (action)
                 {
                     case Constants.ActionDiscover:
-                        Discover(stream, args[1]);
+                        Discover(stream, argument);
                         break;
                     case Constants.ActionRun:
-                        Run(stream, args[1]);
+                        Run(stream, argument);
                         break;
                     default:
                         Usage();
@@ -57,6 +59,18 @@ namespace xunit.runner.worker
             return ExitSuccess;
         }
 
+        private static Stream CreateStream(string pipeName)
+        {
+            if (pipeName == "test")
+            {
+                return new MemoryStream();
+            }
+
+            var namedPipeServerStream = new NamedPipeServerStream(pipeName);
+            namedPipeServerStream.WaitForConnection();
+            return namedPipeServerStream;
+        }
+
         private static void Discover(Stream stream, string assemblyPath)
         {
             Console.WriteLine($"discover started: {assemblyPath}");

xunit.runner.wpf/Impl/RemoteTestUtil.cs

@@ -49,17 +49,18 @@ namespace xunit.runner.wpf.Impl
             }
         }
 
-        private Connection StartWorkerProcess(string action, string argument)
+        private static Connection StartWorkerProcess(string action, string argument)
         {
+            var pipeName = $"xunit.runner.wpf.pipe.{Guid.NewGuid()}";
             var processStartInfo = new ProcessStartInfo();
             processStartInfo.FileName = typeof(xunit.runner.worker.Program).Assembly.Location;
-            processStartInfo.Arguments = $"{action} {argument}";
+            processStartInfo.Arguments = $"{pipeName} {action} {argument}";
             processStartInfo.WindowStyle = ProcessWindowStyle.Hidden;
 
             var process = Process.Start(processStartInfo);
             try
             {
-                var stream = new NamedPipeClientStream(Constants.PipeName);
+                var stream = new NamedPipeClientStream(pipeName);
                 stream.Connect();
                 return new Connection(stream, process);
             }