[http-client-csharp] the post processor should always keep customized code as root documents

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/CSharpGen.cs

@@ -29,7 +29,7 @@ public async Task ExecuteAsync()
             var generatedTestOutputPath = CodeModelPlugin.Instance.Configuration.TestGeneratedDirectory;
 
             GeneratedCodeWorkspace workspace = await GeneratedCodeWorkspace.Create();
-            await CodeModelPlugin.Instance.InitializeSourceInputModelAsync();
+            CodeModelPlugin.Instance.SourceInputModel = new SourceInputModel(await workspace.GetCompilationAsync());
 
             var output = CodeModelPlugin.Instance.OutputLibrary;
             Directory.CreateDirectory(Path.Combine(generatedSourceOutputPath, "Models"));

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/CodeModelPlugin.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
-using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Microsoft.Generator.CSharp.Input;
 using Microsoft.Generator.CSharp.Primitives;
@@ -61,7 +60,17 @@ protected CodeModelPlugin()
 
         // Extensibility points to be implemented by a plugin
         public virtual TypeFactory TypeFactory { get; }
-        public virtual SourceInputModel SourceInputModel => _sourceInputModel ?? throw new InvalidOperationException($"SourceInputModel has not been initialized yet");
+
+        private SourceInputModel? _sourceInputModel;
+        public virtual SourceInputModel SourceInputModel
+        {
+            get => _sourceInputModel ?? throw new InvalidOperationException($"SourceInputModel has not been initialized yet");
+            internal set
+            {
+                _sourceInputModel = value;
+            }
+        }
+
         public virtual string LicenseString => string.Empty;
         public virtual OutputLibrary OutputLibrary { get; } = new();
         public virtual InputLibrary InputLibrary => _inputLibrary;
@@ -89,14 +98,6 @@ public void AddSharedSourceDirectory(string sharedSourceDirectory)
             _sharedSourceDirectories.Add(sharedSourceDirectory);
         }
 
-        private SourceInputModel? _sourceInputModel;
-
-        internal async Task InitializeSourceInputModelAsync()
-        {
-            GeneratedCodeWorkspace existingCode = GeneratedCodeWorkspace.CreateExistingCodeProject([Instance.Configuration.ProjectDirectory], Instance.Configuration.ProjectGeneratedDirectory);
-            _sourceInputModel =  new SourceInputModel(await existingCode.GetCompilationAsync());
-        }
-
         internal HashSet<string> TypesToKeep { get; } = new();
         //TODO consider using TypeProvider so we can have a fully qualified name to filter on
         //https://github.com/microsoft/typespec/issues/4418

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/PostProcessing/GeneratedCodeWorkspace.cs

@@ -34,7 +34,6 @@ internal class GeneratedCodeWorkspace
         private static readonly string[] _sharedFolders = [SharedFolder];
 
         private Project _project;
-        private Compilation? _compilation;
         private Dictionary<string, string> PlainFiles { get; }
 
         private GeneratedCodeWorkspace(Project generatedCodeProject)
@@ -107,7 +106,7 @@ public async Task AddGeneratedFile(CodeFile codefile)
         private async Task<Document> ProcessDocument(Document document)
         {
             var syntaxTree = await document.GetSyntaxTreeAsync();
-            var compilation = await GetProjectCompilationAsync();
+            var compilation = await GetCompilationAsync();
             if (syntaxTree != null)
             {
                 var semanticModel = compilation.GetSemanticModel(syntaxTree);
@@ -143,12 +142,15 @@ private static Project CreateGeneratedCodeProject()
 
         internal static async Task<GeneratedCodeWorkspace> Create()
         {
+            // prepare the generated code project
             var projectTask = Interlocked.Exchange(ref _cachedProject, null);
-            var generatedCodeProject = projectTask != null ? await projectTask : CreateGeneratedCodeProject();
+            var project = projectTask != null ? await projectTask : CreateGeneratedCodeProject();
 
             var outputDirectory = CodeModelPlugin.Instance.Configuration.OutputDirectory;
             var projectDirectory = CodeModelPlugin.Instance.Configuration.ProjectDirectory;
+            var generatedDirectory = CodeModelPlugin.Instance.Configuration.ProjectGeneratedDirectory;
 
+            // add all documents except the documents from the generated directory
             if (Path.IsPathRooted(projectDirectory) && Path.IsPathRooted(outputDirectory))
             {
                 projectDirectory = Path.GetFullPath(projectDirectory);
@@ -157,37 +159,15 @@ internal static async Task<GeneratedCodeWorkspace> Create()
                 Directory.CreateDirectory(projectDirectory);
                 Directory.CreateDirectory(outputDirectory);
 
-                generatedCodeProject = AddDirectory(generatedCodeProject, projectDirectory, skipPredicate: sourceFile => sourceFile.StartsWith(outputDirectory));
+                project = AddDirectory(project, projectDirectory, skipPredicate: sourceFile => sourceFile.StartsWith(generatedDirectory));
             }
 
             foreach (var sharedSourceFolder in CodeModelPlugin.Instance.SharedSourceDirectories)
             {
-                generatedCodeProject = AddDirectory(generatedCodeProject, sharedSourceFolder, folders: _sharedFolders);
+                project = AddDirectory(project, sharedSourceFolder, folders: _sharedFolders);
             }
 
-            generatedCodeProject = generatedCodeProject.WithParseOptions(new CSharpParseOptions(preprocessorSymbols: new[] { "EXPERIMENTAL" }));
-            return new GeneratedCodeWorkspace(generatedCodeProject);
-        }
-
-        internal static GeneratedCodeWorkspace CreateExistingCodeProject(IEnumerable<string> projectDirectories, string generatedDirectory)
-        {
-            var workspace = new AdhocWorkspace();
-            var newOptionSet = workspace.Options.WithChangedOption(FormattingOptions.NewLine, LanguageNames.CSharp, NewLine);
-            workspace.TryApplyChanges(workspace.CurrentSolution.WithOptions(newOptionSet));
-            Project project = workspace.AddProject("ExistingCode", LanguageNames.CSharp);
-
-            foreach (var projectDirectory in projectDirectories)
-            {
-                if (Path.IsPathRooted(projectDirectory))
-                {
-                    project = AddDirectory(project, Path.GetFullPath(projectDirectory), skipPredicate: sourceFile => sourceFile.StartsWith(generatedDirectory));
-                }
-            }
-
-            project = project
-                .AddMetadataReferences(_assemblyMetadataReferences.Value.Concat(CodeModelPlugin.Instance.AdditionalMetadataReferences))
-                .WithCompilationOptions(new CSharpCompilationOptions(
-                    OutputKind.DynamicallyLinkedLibrary, metadataReferenceResolver: _metadataReferenceResolver.Value, nullableContextOptions: NullableContextOptions.Disable));
+            project = project.WithParseOptions(new CSharpParseOptions(preprocessorSymbols: new[] { "EXPERIMENTAL" }));
 
             return new GeneratedCodeWorkspace(project);
         }
@@ -248,11 +228,5 @@ public async Task PostProcessAsync()
                     break;
             }
         }
-
-        private async Task<Compilation> GetProjectCompilationAsync()
-        {
-            _compilation ??= await _project.GetCompilationAsync();
-            return _compilation!;
-        }
     }
 }

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/test/common/Helpers.cs

@@ -1,11 +1,15 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Formatting;
+using NUnit.Framework;
 
 namespace Microsoft.Generator.CSharp.Tests.Common
 {
@@ -43,8 +47,36 @@ public static async Task<Compilation> GetCompilationFromDirectoryAsync(
         {
             var directory = GetAssetFileOrDirectoryPath(false, parameters, method, filePath);
             var codeGenAttributeFiles = Path.Combine(_assemblyLocation, "..", "..", "..", "..", "..", "Microsoft.Generator.CSharp.Customization", "src");
-            var workspace = GeneratedCodeWorkspace.CreateExistingCodeProject([directory, codeGenAttributeFiles], Path.Combine(directory, "Generated"));
-            return await workspace.GetCompilationAsync();
+            var project = CreateExistingCodeProject([directory, codeGenAttributeFiles], Path.Combine(directory, "Generated"));
+            var compilation = await project.GetCompilationAsync();
+            Assert.IsNotNull(compilation);
+            return compilation!;
+        }
+
+        private static Project CreateExistingCodeProject(IEnumerable<string> projectDirectories, string generatedDirectory)
+        {
+            var workspace = new AdhocWorkspace();
+            var newOptionSet = workspace.Options.WithChangedOption(FormattingOptions.NewLine, LanguageNames.CSharp, "\n");
+            workspace.TryApplyChanges(workspace.CurrentSolution.WithOptions(newOptionSet));
+            Project project = workspace.AddProject("ExistingCode", LanguageNames.CSharp);
+
+            foreach (var projectDirectory in projectDirectories)
+            {
+                if (Path.IsPathRooted(projectDirectory))
+                {
+                    project = GeneratedCodeWorkspace.AddDirectory(project, Path.GetFullPath(projectDirectory), skipPredicate: sourceFile => sourceFile.StartsWith(generatedDirectory));
+                }
+            }
+
+            project = project
+                .AddMetadataReferences([
+                    MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
+                    ..CodeModelPlugin.Instance.AdditionalMetadataReferences
+                    ])
+                .WithCompilationOptions(new CSharpCompilationOptions(
+                    OutputKind.DynamicallyLinkedLibrary, metadataReferenceResolver: new WorkspaceMetadataReferenceResolver(), nullableContextOptions: NullableContextOptions.Disable));
+
+            return project;
         }
     }
 }