One way of solving test race condition

Author: GrahamTheCoder

CodeConverter/Shared/CompilationOptionsExtensions.cs

@@ -1,15 +1,13 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.IO;
 using ICSharpCode.CodeConverter.CSharp;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Host.Mef;
 
 namespace ICSharpCode.CodeConverter.Shared
 {
     internal static class CompilationOptionsExtensions
     {
-        private static Lazy<Workspace> Workspace = new Lazy<Workspace>(() => new AdhocWorkspace());
-
         public static Document AddDocumentFromTree(this Project project, SyntaxTree tree)
         {
             return project.AddDocument("CodeToConvert", tree.GetRoot(), filePath: Path.Combine(Directory.GetCurrentDirectory(), "TempCodeToConvert.txt"));
@@ -21,7 +19,7 @@ public static Project CreateProject(this CompilationOptions options, IEnumerable
 
             string projFileExtension = parseOptions.Language == LanguageNames.CSharp ? ".csproj" : ".vbproj";
             var projectFilePath = Path.Combine(Directory.GetCurrentDirectory() + singleDocumentAssemblyName + projFileExtension);
-            var solution = Workspace.Value.CurrentSolution.AddProject(projectId, singleDocumentAssemblyName,
+            var solution = WorkspaceFactory.AdhocSolution.AddProject(projectId, singleDocumentAssemblyName,
                 singleDocumentAssemblyName, options.Language)
                 .WithProjectFilePath(projectId, projectFilePath);
 

CodeConverter/Shared/WorkspaceFactory.cs

@@ -0,0 +1,20 @@
+using System;
+using Microsoft.CodeAnalysis;
+
+namespace ICSharpCode.CodeConverter.Shared
+{
+    public static class WorkspaceFactory
+    {
+        /// <summary>
+        /// Library consumers must use this to guard any non-VS workspace creation (i.e. adhoc or msbuild)
+        /// Know MEF bug means creating multiple workspaces outside VS context in parallel has race conditions: https://github.com/dotnet/roslyn/issues/24260
+        /// </summary>
+        public static object WorkspaceCreationLock = new object();
+        private static Lazy<Solution> LazyAdhocSolution = new Lazy<Solution>(() => {
+            lock (WorkspaceCreationLock) {
+                return new AdhocWorkspace().CurrentSolution;
+            }
+        });
+        public static Solution AdhocSolution => LazyAdhocSolution.Value;
+    }
+}

CommandLine/CodeConv.Shared/MSBuildWorkspaceConverter.cs

@@ -119,7 +119,9 @@ private static MSBuildWorkspace CreateWorkspace(Dictionary<string, string> build
                 MSBuildLocator.RegisterInstance(instance);
                 AppDomain.CurrentDomain.UseVersionAgnosticAssemblyResolution();
             }
-            return MSBuildWorkspace.Create(buildProps);
+            lock (WorkspaceFactory.WorkspaceCreationLock) {
+                return MSBuildWorkspace.Create(buildProps);
+            }
         }
 
         public void Dispose()