Use VS MSBuild.exe instead of dotnet msbuild in no-op tests

Agent-Logs-Url: https://github.com/NuGet/NuGet.Client/sessions/c6cec734-7d92-4cd2-a819-9e05ed4bbacb

Co-authored-by: nkolev92 <[email protected]>

Author: Copilot

test/NuGet.Tests.Apex/NuGet.Tests.Apex/NuGetEndToEndTests/NetCoreProjectTestCase.cs

@@ -252,10 +252,11 @@ public void NetCoreVSAndMSBuildRestoreIsNoOp()
 
             var vsRestoreTimestamp = File.GetLastWriteTime(cacheFilePath.FullName).Ticks;
 
-            // Act - run MSBuild restore externally
+            // Act - run MSBuild restore externally using VS MSBuild
+            var msbuildPath = CommonUtility.GetMSBuildExePath();
             using var process = new Process();
-            process.StartInfo.FileName = "dotnet";
-            process.StartInfo.Arguments = $"msbuild /t:restore \"{testContext.Project.FullPath}\"";
+            process.StartInfo.FileName = msbuildPath;
+            process.StartInfo.Arguments = $"/t:restore \"{testContext.Project.FullPath}\"";
             process.StartInfo.UseShellExecute = false;
             process.StartInfo.RedirectStandardError = true;
             process.Start();
@@ -305,10 +306,11 @@ public void NetCoreMultipleTargetFrameworksVSAndMSBuildRestoreIsNoOp()
 
             var vsRestoreTimestamp = File.GetLastWriteTime(cacheFilePath.FullName).Ticks;
 
-            // Act - run MSBuild restore externally
+            // Act - run MSBuild restore externally using VS MSBuild
+            var msbuildPath = CommonUtility.GetMSBuildExePath();
             using var process = new Process();
-            process.StartInfo.FileName = "dotnet";
-            process.StartInfo.Arguments = $"msbuild /t:restore \"{testContext.Project.FullPath}\"";
+            process.StartInfo.FileName = msbuildPath;
+            process.StartInfo.Arguments = $"/t:restore \"{testContext.Project.FullPath}\"";
             process.StartInfo.UseShellExecute = false;
             process.StartInfo.RedirectStandardError = true;
             process.Start();

test/NuGet.Tests.Apex/NuGet.Tests.Apex/Utility/CommonUtility.cs

@@ -556,5 +556,30 @@ public static void AssertUninstalledPackageByProjectType(VisualStudioHost visual
                 CommonUtility.AssertPackageReferenceDoesNotExist(project, packageName, logger);
             }
         }
+
+        /// <summary>
+        /// Gets the path to MSBuild.exe from the Visual Studio installation.
+        /// Uses the VSAPPIDDIR environment variable to find the VS root folder,
+        /// same approach as Get-MSBuildExe in the PS E2E test infrastructure.
+        /// </summary>
+        public static string GetMSBuildExePath()
+        {
+            string vsAppIdDir = Environment.GetEnvironmentVariable("VSAPPIDDIR") ?? Environment.GetEnvironmentVariable("DevEnvDir");
+            if (string.IsNullOrEmpty(vsAppIdDir))
+            {
+                throw new InvalidOperationException("Could not determine Visual Studio installation path. Neither VSAPPIDDIR nor DevEnvDir environment variable is set.");
+            }
+
+            // VSAPPIDDIR is <VSRoot>\Common7\IDE\, go up 2 levels to get VS root
+            string vsRoot = Path.GetFullPath(Path.Combine(vsAppIdDir, "..", ".."));
+            string msbuildPath = Path.Combine(vsRoot, "MSBuild", "Current", "bin", "MSBuild.exe");
+
+            if (!File.Exists(msbuildPath))
+            {
+                throw new FileNotFoundException($"MSBuild.exe not found at expected path: {msbuildPath}");
+            }
+
+            return msbuildPath;
+        }
     }
 }