Adding a new factory that creates the command as is, without adding the dotnet to it. We need it so that the runner can pass dotnet-test-xunit and get back the final corehost command, which is the right one for VS to use and attach to.

src/Microsoft.DotNet.Cli.Utils/CommandFactory.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Generic;
+using NuGet.Frameworks;
+
+namespace Microsoft.DotNet.Cli.Utils
+{
+    public class CommandFactory : ICommandFactory
+    {
+        public ICommand Create(
+            string commandName,
+            IEnumerable<string> args,
+            NuGetFramework framework = null,
+            string configuration = Constants.DefaultConfiguration)
+        {
+            return Command.Create(commandName, args, framework, configuration);
+        }
+    }
+}

src/Microsoft.DotNet.Cli.Utils/ICommandFactory.cs

@@ -9,6 +9,9 @@ namespace Microsoft.DotNet.Cli.Utils
     public interface ICommandFactory
     {
         ICommand Create(
-            string commandName, IEnumerable<string> args, NuGetFramework framework = null, string configuration = null);
+            string commandName,
+            IEnumerable<string> args,
+            NuGetFramework framework = null,
+            string configuration = Constants.DefaultConfiguration);
     }
 }

src/dotnet/commands/dotnet-test/Program.cs

@@ -130,7 +130,7 @@ namespace Microsoft.DotNet.Tools.Test
                 var messages = new TestMessagesCollection();
                 using (var dotnetTest = new DotnetTest(messages, assemblyUnderTest))
                 {
-                    var commandFactory = new DotNetCommandFactory();
+                    var commandFactory = new CommandFactory();
                     var testRunnerFactory = new TestRunnerFactory(GetCommandName(testRunner), commandFactory);
 
                     dotnetTest

src/dotnet/commands/dotnet-test/ReportingChannel.cs

@@ -129,7 +129,10 @@ namespace Microsoft.DotNet.Tools.Test
 
         public void Dispose()
         {
-            Socket.Dispose();
+            if (Socket != null)
+            {
+                Socket.Dispose();
+            }
         }
     }
 }

src/dotnet/commands/dotnet-test/TestRunners/TestRunner.cs

@@ -51,9 +51,10 @@ namespace Microsoft.DotNet.Tools.Test
             var commandArgs = _argumentsBuilder.BuildArguments();
 
             return _commandFactory.Create(
-                _testRunner,
+                $"dotnet-{_testRunner}",
                 commandArgs,
-                new NuGetFramework("DNXCore", Version.Parse("5.0")));
+                new NuGetFramework("DNXCore", Version.Parse("5.0")),
+                Constants.DefaultConfiguration);
         }
     }
 }

test/dotnet-test.UnitTests/GivenATestRunner.cs

@@ -38,10 +38,10 @@ namespace Microsoft.Dotnet.Tools.Test.Tests
 
             _commandFactoryMock = new Mock<ICommandFactory>();
             _commandFactoryMock.Setup(c => c.Create(
-                _runner,
+                $"dotnet-{_runner}",
                 _testRunnerArguments,
                 new NuGetFramework("DNXCore", Version.Parse("5.0")),
-                null)).Returns(_commandMock.Object).Verifiable();
+                Constants.DefaultConfiguration)).Returns(_commandMock.Object).Verifiable();
         }
 
         [Fact]