Add more multithreaded tests

MSBuild.sln

@@ -78,6 +78,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Build.BuildCheck.
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Build.Templates", "template_feed\Microsoft.Build.Templates.csproj", "{A86EE74A-AEF0-42ED-A5A7-7A54BC0773D8}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.Build.CommandLine.EndToEnd.Tests", "src\MSBuild.EndToEnd.Tests\Microsoft.Build.CommandLine.EndToEnd.Tests.csproj", "{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -862,6 +864,30 @@ Global
 		{A86EE74A-AEF0-42ED-A5A7-7A54BC0773D8}.Release|x64.Build.0 = Release|Any CPU
 		{A86EE74A-AEF0-42ED-A5A7-7A54BC0773D8}.Release|x86.ActiveCfg = Release|Any CPU
 		{A86EE74A-AEF0-42ED-A5A7-7A54BC0773D8}.Release|x86.Build.0 = Release|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|ARM64.ActiveCfg = Debug|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|ARM64.Build.0 = Debug|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|x64.ActiveCfg = Debug|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|x64.Build.0 = Debug|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Debug|x86.Build.0 = Debug|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|Any CPU.ActiveCfg = MachineIndependent|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|Any CPU.Build.0 = MachineIndependent|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|ARM64.ActiveCfg = MachineIndependent|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|ARM64.Build.0 = MachineIndependent|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|x64.ActiveCfg = MachineIndependent|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|x64.Build.0 = MachineIndependent|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|x86.ActiveCfg = MachineIndependent|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.MachineIndependent|x86.Build.0 = MachineIndependent|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|ARM64.ActiveCfg = Release|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|ARM64.Build.0 = Release|arm64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|x64.ActiveCfg = Release|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|x64.Build.0 = Release|x64
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|x86.ActiveCfg = Release|Any CPU
+		{29F9B7E2-F4BE-1C61-B8B5-427BA6463E8F}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

src/BuildCheck.UnitTests/EndToEndTests.cs

@@ -162,7 +162,7 @@ private EmbedResourceTestOutput RunEmbeddedResourceTest(string resourceXmlToAdd,
         const string templateToReplace = "###EmbeddedResourceToAdd";
         TransientTestFolder workFolder = _env.CreateFolder(createFolder: true);
 
-        CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
+        FileSystemUtilities.CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
         ReplaceStringInFile(Path.Combine(workFolder.Path, referencedProjectName, $"{referencedProjectName}.csproj"),
             templateToReplace, resourceXmlToAdd);
         File.Copy(
@@ -198,21 +198,6 @@ void ReplaceStringInFile(string filePath, string original, string replacement)
         }
     }
 
-    private static void CopyFilesRecursively(string sourcePath, string targetPath)
-    {
-        // First Create all directories
-        foreach (string dirPath in Directory.GetDirectories(sourcePath, "*", SearchOption.AllDirectories))
-        {
-            Directory.CreateDirectory(dirPath.Replace(sourcePath, targetPath));
-        }
-
-        // Then copy all the files & Replaces any files with the same name
-        foreach (string newPath in Directory.GetFiles(sourcePath, "*", SearchOption.AllDirectories))
-        {
-            File.Copy(newPath, newPath.Replace(sourcePath, targetPath), true);
-        }
-    }
-
     private static int GetWarningsCount(string output)
     {
         Regex regex = new Regex(@"(\d+) Warning\(s\)");
@@ -272,7 +257,7 @@ public void CopyToOutputTest(bool skipUnchangedDuringCopy)
         const string entryProjectName = "EntryProject";
         TransientTestFolder workFolder = _env.CreateFolder(createFolder: true);
 
-        CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
+        FileSystemUtilities.CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
 
         _env.SetCurrentDirectory(Path.Combine(workFolder.Path, entryProjectName));
 
@@ -377,7 +362,7 @@ public void TFMConfusionCheckTest(string tfmString, string cliSuffix, bool shoul
         const string templateToReplace = "###TFM";
         TransientTestFolder workFolder = _env.CreateFolder(createFolder: true);
 
-        CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
+        FileSystemUtilities.CopyFilesRecursively(Path.Combine(TestAssetsRootPath, testAssetsFolderName), workFolder.Path);
         ReplaceStringInFile(Path.Combine(workFolder.Path, $"{projectName}.csproj"),
             templateToReplace, tfmString);
 

src/MSBuild.EndToEnd.Tests/Microsoft.Build.CommandLine.EndToEnd.Tests.csproj

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>$(RuntimeOutputTargetFrameworks)</TargetFrameworks>
+    <PlatformTarget>$(RuntimeOutputPlatformTarget)</PlatformTarget>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="System.Net.Http" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
+
+    <PackageReference Include="Shouldly" />
+    <PackageReference Include="Verify.Xunit" />
+    <PackageReference Include="Microsoft.IO.Redist" Condition="'$(FeatureMSIORedist)' == 'true'" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Reference Include="System.IO.Compression" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\MSBuild\MSBuild.csproj" />
+    <ProjectReference Include="..\UnitTests.Shared\Microsoft.Build.UnitTests.Shared.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Compile Remove="TestAssets\**\*.cs" />
+    <None Include="TestAssets\**" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
+</Project>

src/MSBuild.EndToEnd.Tests/MultithreadedExecution_Tests.cs

@@ -0,0 +1,149 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.IO;
+using System.Linq;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Logging;
+using Microsoft.Build.Shared;
+using Microsoft.Build.UnitTests;
+using Microsoft.Build.UnitTests.Shared;
+using Shouldly;
+using Xunit;
+using Xunit.Abstractions;
+
+#nullable disable
+
+namespace Microsoft.Build.EndToEndTests
+{
+    /// <summary>
+    /// Tests for multithreaded MSBuild execution scenarios using test assets.
+    /// </summary>
+    public class MultithreadedExecution_Tests : IClassFixture<TestSolutionAssetsFixture>, IDisposable
+    {
+        private readonly ITestOutputHelper _output;
+        private readonly TestEnvironment _env;
+        private readonly string _testAssetDir;
+
+        private readonly int _timeoutInMilliseconds = 60_000;
+
+        // Common parameters for all multithreaded tests:
+        // /nodereuse:false - Prevents MSBuild server processes from persisting between tests,
+        //                    ensuring proper test isolation and avoiding potential timeouts
+        // /v:minimal - Reduces log verbosity for cleaner test output and better performance
+        private const string CommonMSBuildArgs = "/nodereuse:false /v:minimal";
+
+        public MultithreadedExecution_Tests(ITestOutputHelper output, TestSolutionAssetsFixture testAssetFixture)
+        {
+            _output = output;
+            _env = TestEnvironment.Create(output);
+            _testAssetDir = testAssetFixture.TestAssetDir;
+        }
+
+        public void Dispose()
+        {
+            _env.Dispose();
+        }
+
+        /// <summary>
+        /// Prepares an isolated copy of test assets in a temporary directory for each test run.
+        /// This ensures fresh builds and proper test isolation.
+        /// </summary>
+        /// <param name="testAsset">Test asset</param>
+        /// <returns>TestSolutionAsset for the copied asset in a temporary folder.</returns>
+        private TestSolutionAsset PrepareIsolatedTestAssets(TestSolutionAsset testAsset)
+        {
+            string sourceAssetDir = Path.Combine(_testAssetDir, testAsset.SolutionFolder);
+
+            // Ensure source test asset exists
+            Directory.Exists(sourceAssetDir).ShouldBeTrue($"Test asset not found: {sourceAssetDir}.");
+
+            // Create isolated copy of entire test asset directory structure
+            TransientTestFolder workFolder = _env.CreateFolder(createFolder: true);
+
+            FileSystemUtilities.CopyFilesRecursively(sourceAssetDir, workFolder.Path);
+
+            // Return TestSolutionAsset with temp folder and project file
+            return new TestSolutionAsset(workFolder.Path, testAsset.ProjectRelativePath);
+        }
+
+        /// <summary>
+        /// Helper method to resolve TestSolutionAsset instances by name.
+        /// This is the easiest way to work around the limitation that [InlineData] cannot pass complex objects like TestSolutionAsset directly.
+        /// </summary>
+        private static TestSolutionAsset GetTestAssetByName(string testAssetName)
+        {
+            return testAssetName switch
+            {
+                nameof(TestSolutionAssetsFixture.SingleProject) => TestSolutionAssetsFixture.SingleProject,
+                nameof(TestSolutionAssetsFixture.ProjectWithDependencies) => TestSolutionAssetsFixture.ProjectWithDependencies,
+                _ => throw new ArgumentException($"Unknown test asset name: {testAssetName}", nameof(testAssetName))
+            };
+        }
+
+        /// <summary>
+        /// Tests building projects with various multithreading flags.
+        /// </summary>
+        [Theory]
+        [InlineData(nameof(TestSolutionAssetsFixture.SingleProject), "/m:1 /mt")]
+        [InlineData(nameof(TestSolutionAssetsFixture.SingleProject), "/m:8 /mt")]
+        [InlineData(nameof(TestSolutionAssetsFixture.ProjectWithDependencies), "/m:1 /mt")]
+        [InlineData(nameof(TestSolutionAssetsFixture.ProjectWithDependencies), "/m:2 /mt")]
+        [InlineData(nameof(TestSolutionAssetsFixture.ProjectWithDependencies), "/m:8 /mt")]
+        public void MultithreadedBuild_Success(string testAssetName, string multithreadingArgs)
+        {
+            // Resolve TestSolutionAsset from name
+            TestSolutionAsset testAsset = GetTestAssetByName(testAssetName);
+
+            // Prepare isolated copy of test assets to ensure fresh builds
+            TestSolutionAsset isolatedAsset = PrepareIsolatedTestAssets(testAsset);
+
+            string output = RunnerUtilities.ExecBootstrapedMSBuild(
+                $"\"{isolatedAsset.ProjectPath}\" {multithreadingArgs} {CommonMSBuildArgs}", 
+                out bool success, 
+                timeoutMilliseconds: _timeoutInMilliseconds);
+
+            success.ShouldBeTrue($"Build failed with args '{multithreadingArgs}' for {testAsset.SolutionFolder}. Output:\\n{output}");
+
+            _output.WriteLine($"Built {testAsset.SolutionFolder} with arguments {multithreadingArgs}.");
+        }
+
+        /// <summary>
+        /// Tests binary logging with multithreaded builds and verifies replay functionality.
+        /// </summary>
+        [Theory]
+        [InlineData(nameof(TestSolutionAssetsFixture.SingleProject), "/m:8 /mt")]
+        public void MultithreadedBuild_BinaryLogging(string testAssetName, string multithreadingArgs)
+        {
+            // Resolve TestSolutionAsset from name
+            TestSolutionAsset testAsset = GetTestAssetByName(testAssetName);
+
+            // Prepare isolated copy of test assets to ensure fresh builds
+            TestSolutionAsset isolatedAsset = PrepareIsolatedTestAssets(testAsset);
+
+            string binlogPath = Path.Combine(isolatedAsset.SolutionFolder, "build.binlog");
+
+            // Build with binary logging
+            string output = RunnerUtilities.ExecBootstrapedMSBuild(
+                $"\"{isolatedAsset.ProjectPath}\" {multithreadingArgs} /bl:\"{binlogPath}\" {CommonMSBuildArgs}", 
+                out bool success, 
+                timeoutMilliseconds: _timeoutInMilliseconds);
+
+            success.ShouldBeTrue($"Build failed with args '{multithreadingArgs}' for {testAsset.SolutionFolder}. Output:\\n{output}.");
+
+            // Verify binary log was created and has content
+            File.Exists(binlogPath).ShouldBeTrue("Binary log file was not created.");
+
+            // Test binlog replay
+            string replayOutput = RunnerUtilities.ExecBootstrapedMSBuild(
+                $"\"{binlogPath}\" {CommonMSBuildArgs}", 
+                out bool replaySuccess, 
+                timeoutMilliseconds: _timeoutInMilliseconds);
+
+            replaySuccess.ShouldBeTrue($"Binlog replay failed. Output:\\n{replayOutput}");
+
+            _output.WriteLine($"Built and replayed {testAsset.SolutionFolder} with arguments {multithreadingArgs}.");
+        }
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/ConsoleApp/ConsoleApp.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Library1\Library1.csproj" />
+    <ProjectReference Include="..\Library2\Library2.csproj" />
+  </ItemGroup>
+</Project>

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/ConsoleApp/Program.cs

@@ -0,0 +1,9 @@
+namespace ConsoleApp
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+        }
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library1/Class1.cs

@@ -0,0 +1,7 @@
+namespace Library1
+{
+    public class Class1
+    {
+
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library1/Library1.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Library3\Library3.csproj" />
+    <ProjectReference Include="..\Library4\Library4.csproj" />
+  </ItemGroup>
+</Project>

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library2/Class2.cs

@@ -0,0 +1,7 @@
+namespace Library2
+{
+    public class Class2
+    {
+
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library2/Library2.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Library3\Library3.csproj" />
+    <ProjectReference Include="..\Library4\Library4.csproj" />
+  </ItemGroup>
+</Project>

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library3/Class3.cs

@@ -0,0 +1,7 @@
+namespace Library3
+{
+    public class Class3
+    {
+
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library3/Library3.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+</Project>

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library4/Class4.cs

@@ -0,0 +1,7 @@
+namespace Library3
+{
+    public class Class3
+    {
+
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/ProjectWithDependencies/Library4/Library4.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+</Project>

src/MSBuild.EndToEnd.Tests/TestAssets/SingleProject/Program.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace ConsoleApp
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+
+        }
+    }
+}

src/MSBuild.EndToEnd.Tests/TestAssets/SingleProject/SingleProject.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>