Test MSBuildWorkspace opening dotnet new projects.

src/Workspaces/Core/MSBuild.BuildHost/Build/ProjectBuildManager.cs

@@ -226,20 +226,21 @@ public void EndBatchBuild()
         {
             Debug.Assert(BatchBuildStarted);
 
-            var targets = new[] { TargetNames.Compile, TargetNames.CoreCompile };
+            var requiredTargets = new[] { TargetNames.Compile, TargetNames.CoreCompile };
+            var optionalTargets = new[] { TargetNames.DesignTimeMarkupCompilation };
 
-            return BuildProjectAsync(project, targets, log, cancellationToken);
+            return BuildProjectAsync(project, requiredTargets, optionalTargets, log, cancellationToken);
         }
 
         private async Task<MSB.Execution.ProjectInstance> BuildProjectAsync(
-            MSB.Evaluation.Project project, string[] targets, DiagnosticLog log, CancellationToken cancellationToken)
+            MSB.Evaluation.Project project, string[] requiredTargets, string[] optionalTargets, DiagnosticLog log, CancellationToken cancellationToken)
         {
             // create a project instance to be executed by build engine.
             // The executed project will hold the final model of the project after execution via msbuild.
             var projectInstance = project.CreateProjectInstance();
 
             // Verify targets
-            foreach (var target in targets)
+            foreach (var target in requiredTargets)
             {
                 if (!projectInstance.Targets.ContainsKey(target))
                 {
@@ -248,9 +249,18 @@ public void EndBatchBuild()
                 }
             }
 
+            var targets = new List<string>(requiredTargets);
+            foreach (var target in optionalTargets)
+            {
+                if (projectInstance.Targets.ContainsKey(target))
+                {
+                    targets.Add(target);
+                }
+            }
+
             _batchBuildLogger?.SetProjectAndLog(projectInstance.FullPath, log);
 
-            var buildRequestData = new MSB.Execution.BuildRequestData(projectInstance, targets);
+            var buildRequestData = new MSB.Execution.BuildRequestData(projectInstance, targets.ToArray());
 
             var result = await BuildAsync(buildRequestData, cancellationToken).ConfigureAwait(false);
 

src/Workspaces/Core/MSBuild.BuildHost/MSBuild/Constants/TargetNames.cs

@@ -8,5 +8,6 @@ internal static class TargetNames
     {
         public const string Compile = nameof(Compile);
         public const string CoreCompile = nameof(CoreCompile);
+        public const string DesignTimeMarkupCompilation = nameof(DesignTimeMarkupCompilation);
     }
 }

src/Workspaces/MSBuildTest/NewlyCreatedProjectsFromDotNetNew.cs

@@ -0,0 +1,264 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Shared.Extensions;
+using Roslyn.Test.Utilities;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Microsoft.CodeAnalysis.MSBuild.UnitTests
+{
+    public class NewlyCreatedProjectsFromDotNetNew : MSBuildWorkspaceTestBase
+    {
+        private static readonly string s_globalJsonPath;
+
+        // The Maui templates require additional dotnet workloads to be installed.
+        // Running `dotnet workload restore` will install workloads but may require
+        // admin permissions. In addition a restart may be required after workload
+        // installation.
+        private const bool ExcludeMauiTemplates = true;
+
+        protected ITestOutputHelper TestOutputHelper { get; set; }
+
+        static NewlyCreatedProjectsFromDotNetNew()
+        {
+            // We'll use the same global.json as we use for our own build.
+            s_globalJsonPath = Path.Combine(GetSolutionFolder(), "global.json");
+
+            static string GetSolutionFolder()
+            {
+                // Expected assembly path:
+                //  <solutionFolder>\artifacts\bin\Microsoft.CodeAnalysis.Workspaces.MSBuild.UnitTests\<Configuration>\<TFM>\Microsoft.CodeAnalysis.Workspaces.MSBuild.UnitTests.dll
+                var assemblyLocation = typeof(DotNetSdkMSBuildInstalled).Assembly.Location;
+                var solutionFolder = Directory.GetParent(assemblyLocation)
+                    ?.Parent?.Parent?.Parent?.Parent?.Parent?.FullName;
+                Assumes.NotNull(solutionFolder);
+                return solutionFolder;
+            }
+        }
+
+        public NewlyCreatedProjectsFromDotNetNew(ITestOutputHelper output)
+        {
+            TestOutputHelper = output;
+        }
+
+        [ConditionalTheory(typeof(DotNetSdkMSBuildInstalled))]
+        [MemberData(nameof(GetCSharpProjectTemplateNames), DisableDiscoveryEnumeration = false)]
+        public async Task ValidateCSharpTemplateProjects(string templateName)
+        {
+            var ignoredDiagnostics = templateName switch
+            {
+                "blazor" or "blazorwasm" or "blazorwasm-empty" =>
+                    [
+                        // The type or namespace name {'csharp_blazor_project'|'App'} could not be found
+                        // (are you missing a using directive or an assembly reference?)
+                        // Bug: https://github.com/dotnet/roslyn/issues/72015
+                        "CS0246",
+                    ],
+                _ => Array.Empty<string>(),
+            };
+
+            await AssertTemplateProjectLoadsCleanlyAsync(templateName, LanguageNames.CSharp, ignoredDiagnostics);
+        }
+
+        [ConditionalTheory(typeof(DotNetSdkMSBuildInstalled))]
+        [MemberData(nameof(GetVisualBasicProjectTemplateNames), DisableDiscoveryEnumeration = false)]
+        public async Task ValidateVisualBasicTemplateProjects(string templateName)
+        {
+            var ignoredDiagnostics = !ExecutionConditionUtil.IsWindows
+                ? [
+                    // Type 'Global.Microsoft.VisualBasic.ApplicationServices.ApplicationBase' is not defined.
+                    // Bug: https://github.com/dotnet/roslyn/issues/72014
+                    "BC30002",
+                ]
+                : Array.Empty<string>();
+
+            await AssertTemplateProjectLoadsCleanlyAsync(templateName, LanguageNames.VisualBasic, ignoredDiagnostics);
+        }
+
+        public static TheoryData<string> GetCSharpProjectTemplateNames()
+            => GetProjectTemplateNames("c#");
+
+        public static TheoryData<string> GetVisualBasicProjectTemplateNames()
+            => GetProjectTemplateNames("vb");
+
+        public static TheoryData<string> GetProjectTemplateNames(string language)
+        {
+            // The expected output from the list command is as follows.
+
+            // These templates matched your input: --language='vb', --type='project'
+            //
+            // Template Name                  Short Name           Language  Tags
+            // -----------------------------  -------------------  --------  ---------------
+            // Class Library                  classlib             C#,F#,VB  Common/Library
+            // Console App                    console              C#,F#,VB  Common/Console
+            // ...
+
+            var result = RunDotNet($"new list --type project --language {language}", output: null);
+
+            var lines = result.Output.Split(new[] { "\r", "\n" }, StringSplitOptions.RemoveEmptyEntries);
+
+            TheoryData<string> templateNames = [];
+            var foundDivider = false;
+
+            foreach (var line in lines)
+            {
+                if (!foundDivider)
+                {
+                    if (line.StartsWith("----"))
+                    {
+                        foundDivider = true;
+                    }
+                    continue;
+                }
+
+                var columns = line.Split(new[] { "  " }, StringSplitOptions.RemoveEmptyEntries)
+                    .Select(c => c.Trim())
+                    .ToArray();
+                var templateShortName = columns[1].Split(',').First();
+
+                if (ExcludeMauiTemplates && templateShortName.StartsWith("maui"))
+                    continue;
+
+                templateNames.Add(templateShortName);
+            }
+
+            Assert.True(foundDivider);
+
+            return templateNames;
+        }
+
+        private async Task AssertTemplateProjectLoadsCleanlyAsync(string templateName, string languageName, string[]? ignoredDiagnostics = null)
+        {
+            if (ignoredDiagnostics?.Length > 0)
+            {
+                TestOutputHelper.WriteLine($"Ignoring compiler diagnostics: \"{string.Join("\", \"", ignoredDiagnostics)}\"");
+            }
+
+            var projectDirectory = SolutionDirectory.Path;
+            var projectFilePath = GetProjectFilePath(projectDirectory, languageName);
+
+            CreateNewProject(templateName, projectDirectory, languageName, TestOutputHelper);
+
+            await AssertProjectLoadsCleanlyAsync(projectFilePath, ignoredDiagnostics ?? []);
+
+            return;
+
+            static string GetProjectFilePath(string projectDirectory, string languageName)
+            {
+                var projectName = new DirectoryInfo(projectDirectory).Name;
+                var projectExtension = languageName switch
+                {
+                    LanguageNames.CSharp => "csproj",
+                    LanguageNames.VisualBasic => "vbproj",
+                    _ => throw new ArgumentOutOfRangeException(nameof(languageName), actualValue: languageName, message: "Only C# and VB.NET projects are supported.")
+                };
+                return Path.Combine(projectDirectory, $"{projectName}.{projectExtension}");
+            }
+
+            static void CreateNewProject(string templateName, string outputDirectory, string languageName, ITestOutputHelper output)
+            {
+                var language = languageName switch
+                {
+                    LanguageNames.CSharp => "C#",
+                    LanguageNames.VisualBasic => "VB",
+                    _ => throw new ArgumentOutOfRangeException(nameof(languageName), actualValue: languageName, message: "Only C# and VB.NET projects are supported.")
+                };
+
+                TryCopyGlobalJson(outputDirectory);
+
+                var newResult = RunDotNet($"new \"{templateName}\" -o \"{outputDirectory}\" --language \"{language}\"", output, outputDirectory);
+
+                // Most templates invoke restore as a post-creation action. However, some, like the
+                // Maui templates, do not run restore since they require additional workloads to be
+                // installed.
+                if (newResult.Output.Contains("Restoring"))
+                {
+                    return;
+                }
+
+                try
+                {
+                    // Attempt a restore and see if we are instructed to install additional workloads.
+                    var restoreResult = RunDotNet($"restore", output, outputDirectory);
+                }
+                catch (InvalidOperationException ex) when (ex.Message.Contains("command: dotnet workload restore"))
+                {
+                    throw new InvalidOperationException($"The '{templateName}' template requires additional dotnet workloads to be installed. It should be excluded during template discovery. " + ex.Message);
+                }
+            }
+
+            static void TryCopyGlobalJson(string outputDirectory)
+            {
+                var tempGlobalJsonPath = Path.Combine(outputDirectory, "global.json");
+                try
+                {
+                    File.Copy(s_globalJsonPath, tempGlobalJsonPath);
+                }
+                catch (FileNotFoundException)
+                {
+                }
+            }
+
+            static async Task AssertProjectLoadsCleanlyAsync(string projectFilePath, string[] ignoredDiagnostics)
+            {
+                using var workspace = CreateMSBuildWorkspace();
+                var project = await workspace.OpenProjectAsync(projectFilePath, cancellationToken: CancellationToken.None);
+
+                AssertEx.Empty(workspace.Diagnostics, $"The following workspace diagnostics are being reported for the template.");
+
+                var compilation = await project.GetRequiredCompilationAsync(CancellationToken.None);
+
+                // Unnecessary using directives are reported with a severity of Hidden
+                var nonHiddenDiagnostics = compilation!.GetDiagnostics()
+                    .Where(diagnostic => diagnostic.Severity > DiagnosticSeverity.Hidden)
+                    .ToImmutableArray();
+
+                // For good test hygiene lets ensure that all ignored diagnostics were actually reported.
+                var reportedDiagnosticIds = nonHiddenDiagnostics
+                    .Select(diagnostic => diagnostic.Id)
+                    .ToImmutableHashSet();
+                var unnecessaryIgnoreDiagnostics = ignoredDiagnostics
+                    .Where(id => !reportedDiagnosticIds.Contains(id));
+
+                AssertEx.Empty(unnecessaryIgnoreDiagnostics, $"The following diagnostics are unnecessarily being ignored for the template.");
+
+                var filteredDiagnostics = nonHiddenDiagnostics
+                    .Where(diagnostic => !ignoredDiagnostics.Contains(diagnostic.Id));
+
+                AssertEx.Empty(filteredDiagnostics, $"The following compiler diagnostics are being reported for the template.");
+            }
+        }
+
+        private static ProcessResult RunDotNet(string arguments, ITestOutputHelper? output, string? workingDirectory = null)
+        {
+            var dotNetExeName = "dotnet" + (Path.DirectorySeparatorChar == '/' ? "" : ".exe");
+
+            var result = ProcessUtilities.Run(dotNetExeName, arguments, workingDirectory, additionalEnvironmentVars: [new KeyValuePair<string, string>("DOTNET_CLI_UI_LANGUAGE", "en")]);
+
+            if (result.ExitCode != 0)
+            {
+                throw new InvalidOperationException(string.Join(Environment.NewLine,
+                    [
+                        $"`dotnet {arguments}` returned a non-zero exit code.",
+                        "Output:",
+                        result.Output,
+                        "Error:",
+                        result.Errors
+                    ]));
+            }
+
+            output?.WriteLine(result.Output);
+
+            return result;
+        }
+    }
+}