Honor --arch switch for arm64 on Windows and Mac

src/Microsoft.TestPlatform.CoreUtilities/Helpers/DotnetHostHelper.cs

@@ -26,12 +26,13 @@ internal class DotnetHostHelper : IDotnetHostHelper
         private readonly IEnvironment environment;
         private readonly IWindowsRegistryHelper windowsRegistryHelper;
         private readonly IEnvironmentVariableHelper environmentVariableHelper;
+        private readonly IProcessHelper processHelper;
         private readonly string muxerName;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DotnetHostHelper"/> class.
         /// </summary>
-        public DotnetHostHelper() : this(new FileHelper(), new PlatformEnvironment(), new WindowsRegistryHelper(), new EnvironmentVariableHelper())
+        public DotnetHostHelper() : this(new FileHelper(), new PlatformEnvironment(), new WindowsRegistryHelper(), new EnvironmentVariableHelper(), new ProcessHelper())
         {
         }
 
@@ -43,12 +44,14 @@ public DotnetHostHelper(
             IFileHelper fileHelper,
             IEnvironment environment,
             IWindowsRegistryHelper windowsRegistryHelper,
-            IEnvironmentVariableHelper environmentVariableHelper)
+            IEnvironmentVariableHelper environmentVariableHelper,
+            IProcessHelper processHelper)
         {
             this.fileHelper = fileHelper;
             this.environment = environment;
             this.windowsRegistryHelper = windowsRegistryHelper;
             this.environmentVariableHelper = environmentVariableHelper;
+            this.processHelper = processHelper;
             this.muxerName = $"dotnet{(environment.OperatingSystem == PlatformOperatingSystem.Windows ? ".exe" : "")}";
         }
 
@@ -103,6 +106,21 @@ private bool TryGetExecutablePath(string executableBaseName, out string executab
 
         public bool TryGetDotnetPathByArchitecture(PlatformArchitecture targetArchitecture, out string muxerPath)
         {
+            if (this.environment.Architecture == targetArchitecture)
+            {
+                string currentProcessFileName = this.processHelper.GetCurrentProcessFileName();
+                if (Path.GetFileName(currentProcessFileName) != this.muxerName)
+                {
+                    EqtTrace.Verbose($"DotnetHostHelper: Target architecture same as current process architecture but muxer is not a valid one, '{currentProcessFileName}'");
+                }
+                else
+                {
+                    muxerPath = currentProcessFileName;
+                    EqtTrace.Verbose($"DotnetHostHelper: Target architecture same as current process architecture, muxer resolved using current process path '{muxerPath}'");
+                    return true;
+                }
+            }
+
             // We used similar approach as the runtime resolver.
             // https://github.com/dotnet/runtime/blob/main/src/native/corehost/fxr_resolver.cpp#L55
 

test/Microsoft.TestPlatform.CoreUtilities.UnitTests/Helpers/DotnetHostHelperTest.cs

@@ -26,14 +26,15 @@ public void GetDotnetPathByArchitecture_EnvVars(PlatformArchitecture targetArchi
         {
             string expectedMuxerLocation = platformSystem == PlatformOperatingSystem.OSX ? "/tmp/dotnet" : @"c:\dotnet.exe";
             Mock<IFileHelper> fileHelper = new Mock<IFileHelper>();
+            Mock<IProcessHelper> processHelper = new Mock<IProcessHelper>();
             Mock<IEnvironment> environmentHelper = new Mock<IEnvironment>();
             environmentHelper.SetupGet(x => x.Architecture).Returns(platformArchitecture);
             environmentHelper.SetupGet(x => x.OperatingSystem).Returns(platformSystem);
             Mock<IWindowsRegistryHelper> windowsRegistrytHelper = new Mock<IWindowsRegistryHelper>();
             Mock<IEnvironmentVariableHelper> environmentVariableHelper = new Mock<IEnvironmentVariableHelper>();
             environmentVariableHelper.Setup(x => x.GetEnvironmentVariable(envVar)).Returns(expectedMuxerLocation);
 
-            var dotnetHostHelper = new DotnetHostHelper(fileHelper.Object, environmentHelper.Object, windowsRegistrytHelper.Object, environmentVariableHelper.Object);
+            var dotnetHostHelper = new DotnetHostHelper(fileHelper.Object, environmentHelper.Object, windowsRegistrytHelper.Object, environmentVariableHelper.Object, processHelper.Object);
         }
     }
 }

test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/ProxyOperationManagerTests.cs

@@ -15,7 +15,6 @@ namespace TestPlatform.CrossPlatEngine.UnitTests.Client
     using Microsoft.VisualStudio.TestPlatform.CommunicationUtilities;
     using Microsoft.VisualStudio.TestPlatform.CommunicationUtilities.Interfaces;
     using Microsoft.VisualStudio.TestPlatform.CommunicationUtilities.ObjectModel;
-    using Microsoft.VisualStudio.TestPlatform.CommunicationUtilities.Resources;
     using Microsoft.VisualStudio.TestPlatform.CoreUtilities.Helpers;
     using Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client;
     using Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Helpers;
@@ -24,12 +23,10 @@ namespace TestPlatform.CrossPlatEngine.UnitTests.Client
     using Microsoft.VisualStudio.TestPlatform.ObjectModel.Client;
     using Microsoft.VisualStudio.TestPlatform.ObjectModel.Host;
     using Microsoft.VisualStudio.TestPlatform.PlatformAbstractions.Interfaces;
-    using Microsoft.VisualStudio.TestPlatform.Utilities.Helpers;
     using Microsoft.VisualStudio.TestPlatform.Utilities.Helpers.Interfaces;
     using Microsoft.VisualStudio.TestTools.UnitTesting;
 
     using Moq;
-    using Constants = Microsoft.VisualStudio.TestPlatform.CoreUtilities.Constants;
 
     [TestClass]
     public class ProxyOperationManagerTests : ProxyBaseManagerTests
@@ -546,7 +543,7 @@ public TestableDotnetTestHostManager(
                 IEnvironmentVariableHelper environmentVariableHelper) : base(
                     processHelper,
                     fileHelper,
-                    new DotnetHostHelper(fileHelper, environment, new WindowsRegistryHelper(), new EnvironmentVariableHelper()),
+                    new DotnetHostHelper(fileHelper, environment, windowsRegistryHelper, environmentVariableHelper, processHelper),
                     environment,
                     runsettingHelper,
                     windowsRegistryHelper,

test/Microsoft.TestPlatform.TestHostProvider.UnitTests/Hosting/DotnetTestHostManagerTests.cs

@@ -9,7 +9,6 @@ namespace TestPlatform.TestHostProvider.UnitTests.Hosting
     using System.IO;
     using System.Linq;
     using System.Reflection;
-    using System.Runtime.InteropServices;
     using System.Text;
     using System.Threading;
     using System.Threading.Tasks;
@@ -88,7 +87,7 @@ public DotnetTestHostManagerTests()
             this.dotnetHostManager = new TestableDotnetTestHostManager(
                                          this.mockProcessHelper.Object,
                                          this.mockFileHelper.Object,
-                                         new DotnetHostHelper(this.mockFileHelper.Object, this.mockEnvironment.Object, this.mockWindowsRegistry.Object, this.mockEnvironmentVariable.Object),
+                                         new DotnetHostHelper(this.mockFileHelper.Object, this.mockEnvironment.Object, this.mockWindowsRegistry.Object, this.mockEnvironmentVariable.Object, this.mockProcessHelper.Object),
                                          this.mockEnvironment.Object,
                                          this.mockRunsettingHelper.Object,
                                          this.mockWindowsRegistry.Object,