Embed solution node into a graph

src/Build.UnitTests/BackEnd/BuildManager_Tests.cs

@@ -4496,6 +4496,81 @@ public void GraphBuildShouldBeAbleToConstructGraphButSkipBuild()
             logger.FullLog.ShouldContain("3 nodes, 2 edges");
         }
 
+        [Fact]
+        public void GraphBuildSolutionIncludesSyntheticSolutionNodeInResults()
+        {
+            using TestEnvironment env = TestEnvironment.Create(_output);
+            ProjectCollection projectCollection = env.CreateProjectCollection().Collection;
+
+            TransientTestFolder root = env.CreateFolder(createFolder: true);
+            TransientTestFolder projectFolder = env.CreateFolder(Path.Combine(root.Path, "SimpleProject"), createFolder: true);
+            env.CreateFile(projectFolder, "SimpleProject.csproj",
+                """
+                <Project>
+                  <Target Name="Build">
+                    <Message Text="ProjectBuilt" Importance="High" />
+                  </Target>
+                </Project>
+                """);
+
+            TransientTestFile solutionFile = env.CreateFile(root, "SimpleProject.sln",
+                """
+                Microsoft Visual Studio Solution File, Format Version 12.00
+                # Visual Studio Version 16
+                VisualStudioVersion = 16.0.29326.124
+                MinimumVisualStudioVersion = 10.0.40219.1
+                Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SimpleProject", "SimpleProject\SimpleProject.csproj", "{79B5EBA6-5D27-4976-BC31-14422245A59A}"
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Debug|Any CPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {79B5EBA6-5D27-4976-BC31-14422245A59A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {79B5EBA6-5D27-4976-BC31-14422245A59A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                """);
+
+            env.CreateFile(root, $"after.{Path.GetFileName(solutionFile.Path)}.targets",
+                """
+                <Project>
+                  <Target Name="AfterSolutionHook" AfterTargets="Build">
+                    <Message Text="AfterSolutionHookRan" Importance="High" />
+                  </Target>
+                </Project>
+                """);
+
+            ProjectGraph graph = new(new ProjectGraphEntryPoint(solutionFile.Path), projectCollection);
+            graph.EntryPointNodes.Count.ShouldBe(1);
+            graph.ProjectNodes.Contains(graph.EntryPointNodes.Single()).ShouldBeFalse();
+
+            ProjectGraphNode syntheticSolutionNode = graph.EntryPointNodes.Single();
+
+            GraphBuildRequestData request = new(graph, Array.Empty<string>(), projectCollection.HostServices);
+
+            GraphBuildResult result = _buildManager.Build(_parameters, request);
+            result.OverallResult.ShouldBe(BuildResultCode.Success);
+
+            // ResultsByNode should include both project nodes AND the synthetic solution node
+            result.ResultsByNode.Count.ShouldBe(graph.ProjectNodes.Count + 1);
+            foreach (ProjectGraphNode graphNode in graph.ProjectNodes)
+            {
+                result.ResultsByNode.ContainsKey(graphNode).ShouldBeTrue();
+            }
+
+            // Verify synthetic solution node is included in results
+            result.ResultsByNode.ContainsKey(syntheticSolutionNode).ShouldBeTrue();
+            result.ResultsByNode[syntheticSolutionNode].OverallResult.ShouldBe(BuildResultCode.Success);
+
+            // Verify that both the project and solution hooks ran (addresses Rainer's review comment)
+            _logger.AssertLogContains("ProjectBuilt");
+            _logger.AssertLogContains("AfterSolutionHookRan");
+        }
+
         /// <summary>
         /// Helper task used by <see cref="TaskInputLoggingIsExposedToTasks"/> to verify <see cref="TaskLoggingHelper.IsTaskInputLoggingEnabled"/>.
         /// </summary>

src/Build.UnitTests/BinaryLogger_Tests.cs

@@ -521,6 +521,60 @@ public void BinaryLoggerShouldEmbedFilesWithRelativePathFromChildProjects()
             generatedFileCount.ShouldBe(2, $"Embedded files: {string.Join(",", zipArchive.Entries)}");
         }
 
+        [Fact]
+        public void BinaryLoggerGraphBuildSolutionEmbedsSolutionFile()
+        {
+            TransientTestFolder root = _env.CreateFolder(createFolder: true);
+            TransientTestFolder projectFolder = _env.CreateFolder(Path.Combine(root.Path, "SimpleProject"), createFolder: true);
+            _env.CreateFile(projectFolder, "SimpleProject.csproj",
+                """
+                <Project>
+                  <Target Name="Build">
+                    <Message Text="ProjectBuilt" Importance="High" />
+                  </Target>
+                </Project>
+                """);
+
+            TransientTestFile solutionFile = _env.CreateFile(root, "SimpleProject.sln",
+                """
+                Microsoft Visual Studio Solution File, Format Version 12.00
+                # Visual Studio Version 16
+                VisualStudioVersion = 16.0.29326.124
+                MinimumVisualStudioVersion = 10.0.40219.1
+                Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SimpleProject", "SimpleProject\SimpleProject.csproj", "{79B5EBA6-5D27-4976-BC31-14422245A59A}"
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Debug|Any CPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {79B5EBA6-5D27-4976-BC31-14422245A59A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {79B5EBA6-5D27-4976-BC31-14422245A59A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                """);
+
+            RunnerUtilities.ExecMSBuild(
+                $"\"{solutionFile.Path}\" /graphBuild /bl:\"{_logFile};ProjectImports=ZipFile\"",
+                out bool success);
+            success.ShouldBeTrue();
+
+            string projectImportsZipPath = Path.ChangeExtension(_logFile, ".ProjectImports.zip");
+            using var fileStream = new FileStream(projectImportsZipPath, FileMode.Open);
+            using var zipArchive = new ZipArchive(fileStream, ZipArchiveMode.Read);
+
+            string solutionFileName = Path.GetFileName(solutionFile.Path);
+            ZipArchiveEntry embeddedSolutionEntry = zipArchive.Entries
+                .FirstOrDefault(entry => entry.Name.Equals(solutionFileName, StringComparison.OrdinalIgnoreCase));
+
+            embeddedSolutionEntry.ShouldNotBeNull(
+                $"Expected solution file '{solutionFileName}' in project imports archive. Embedded files: {string.Join(",", zipArchive.Entries.Select(e => e.FullName))}");
+            embeddedSolutionEntry.Length.ShouldBeGreaterThan(0);
+        }
+
         [RequiresSymbolicLinksFact]
         public void BinaryLoggerShouldEmbedSymlinkFilesViaTaskOutput()
         {

src/Build.UnitTests/Graph/GraphLoadedFromSolution_tests.cs

@@ -687,15 +687,13 @@ private void AssertSolutionBasedGraph(
             // Exactly 1 node per project
             graph.ProjectNodes.Count.ShouldBe(graph.ProjectNodes.Select(GetProjectPath).Distinct().Count());
 
-            // in the solution, all nodes are entry points
-            graphFromSolution.EntryPointNodes.Select(GetProjectPath)
-                .ShouldBeSetEquivalentTo(graph.ProjectNodes.Select(GetProjectPath));
+            graphFromSolution.EntryPointNodes.Count.ShouldBe(1);
+            graphFromSolution.EntryPointNodes.First().ProjectInstance.FullPath.ShouldBe(solutionPath);
+            graphFromSolution.GraphRoots.Count.ShouldBe(1);
+            graphFromSolution.GraphRoots.First().ProjectInstance.FullPath.ShouldBe(solutionPath);
 
             if (projectConfigurations == null || graphFromSolution.ProjectNodes.All(n => n.ProjectReferences.Count == 0))
             {
-                graphFromSolution.GraphRoots.Select(GetProjectPath)
-                    .ShouldBeSameIgnoringOrder(graph.GraphRoots.Select(GetProjectPath));
-
                 graphFromSolution.ProjectNodes.Select(GetProjectPath)
                     .ShouldBeSameIgnoringOrder(graph.ProjectNodes.Select(GetProjectPath));
             }

src/Build.UnitTests/Graph/ProjectGraph_Tests.cs

@@ -860,10 +860,10 @@ public void ConstructGraphWithSolution()
                 project8Xml.Save(project8Path);
 
                 var projectGraph = new ProjectGraph(slnFile.Path);
-                projectGraph.EntryPointNodes.Count.ShouldBe(5);
-                projectGraph.EntryPointNodes.Select(node => node.ProjectInstance.FullPath).ShouldBe(new[] { project1Path, project2Path, project3Path, project6Path, project8Path }, ignoreOrder: true);
-                projectGraph.GraphRoots.Count.ShouldBe(2);
-                projectGraph.GraphRoots.Select(node => node.ProjectInstance.FullPath).ShouldBe(new[] { project1Path, project6Path }, ignoreOrder: true);
+                projectGraph.EntryPointNodes.Count.ShouldBe(1);
+                projectGraph.EntryPointNodes.Single().ProjectInstance.FullPath.ShouldBe(slnFile.Path);
+                projectGraph.GraphRoots.Count.ShouldBe(1);
+                projectGraph.GraphRoots.Single().ProjectInstance.FullPath.ShouldBe(slnFile.Path);
                 projectGraph.ProjectNodes.Count.ShouldBe(7);
 
                 ProjectGraphNode project1Node = projectGraph.ProjectNodes.Single(node => node.ProjectInstance.FullPath == project1Path);