Add NetCoreMultipleTargetFrameworksVSAndMSBuildRestoreIsNoOp test for multi-targeted projects

Agent-Logs-Url: https://github.com/NuGet/NuGet.Client/sessions/247a9488-be33-43c9-9494-fadabefae6c8

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

Author: Copilot

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

@@ -1,7 +1,9 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Threading.Tasks;
+using System.Xml.Linq;
 using Microsoft.Test.Apex.VisualStudio.Solution;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -269,6 +271,59 @@ public void NetCoreVSAndMSBuildRestoreIsNoOp()
                 "MSBuild restore should be a no-op after VS restore - cache file timestamp should not change.");
         }
 
+        // Migrated from Test-NetCoreMultipleTargetFrameworksVSandMSBuildNoOp in NetCoreProjectTest.ps1
+        [TestMethod]
+        [Timeout(DefaultTimeout)]
+        public void NetCoreMultipleTargetFrameworksVSAndMSBuildRestoreIsNoOp()
+        {
+            // Arrange - create project and modify it to be multi-targeted
+            using var testContext = new ApexTestContext(VisualStudio, ProjectTemplate.NetCoreConsoleApp, Logger, addNetStandardFeeds: true);
+
+            testContext.Project.Save();
+            var doc = XDocument.Load(testContext.Project.FullPath);
+            var ns = doc.Root.Name.Namespace;
+
+            // Switch TargetFramework to TargetFrameworks with multiple TFMs
+            var tfElement = doc.Root.Descendants(ns + "TargetFramework").FirstOrDefault();
+            if (tfElement != null)
+            {
+                tfElement.Name = ns + "TargetFrameworks";
+                tfElement.Value = "net8.0;netstandard2.0";
+            }
+
+            // Remove OutputType since netstandard2.0 doesn't support Exe
+            var outputTypeElement = doc.Root.Descendants(ns + "OutputType").FirstOrDefault();
+            outputTypeElement?.Remove();
+
+            doc.Save(testContext.Project.FullPath);
+
+            testContext.SolutionService.Build();
+            testContext.NuGetApexTestService.WaitForAutoRestore();
+
+            var cacheFilePath = CommonUtility.GetCacheFilePath(testContext.Project.FullPath);
+            CommonUtility.WaitForFileExists(cacheFilePath);
+
+            var vsRestoreTimestamp = File.GetLastWriteTime(cacheFilePath.FullName).Ticks;
+
+            // Act - run MSBuild restore externally
+            using var process = new Process();
+            process.StartInfo.FileName = "dotnet";
+            process.StartInfo.Arguments = $"msbuild /t:restore \"{testContext.Project.FullPath}\"";
+            process.StartInfo.UseShellExecute = false;
+            process.StartInfo.RedirectStandardError = true;
+            process.Start();
+            string standardError = process.StandardError.ReadToEnd();
+            process.WaitForExit();
+
+            Assert.AreEqual(0, process.ExitCode, $"MSBuild restore failed: {standardError}");
+
+            var msbuildRestoreTimestamp = File.GetLastWriteTime(cacheFilePath.FullName).Ticks;
+
+            // Assert - MSBuild restore should be a no-op for multi-targeted project
+            Assert.AreEqual(vsRestoreTimestamp, msbuildRestoreTimestamp,
+                "MSBuild restore should be a no-op after VS restore for multi-targeted project - cache file timestamp should not change.");
+        }
+
         // There  is a bug with VS or Apex where NetCoreConsoleApp and NetCoreClassLib create netcore 2.1 projects that are not supported by the sdk
         // Commenting out any NetCoreConsoleApp or NetCoreClassLib template and swapping it for NetStandardClassLib as both are package ref.