Simplify the project snapshot manager API a bit and break a few dependencies (#9864)

One of the key challenges in rationalizing our various DI containers is
`ProjectSnapshotManager`. The position of this service in the dependency
graph creates cycles that are currently broken by indirecting through
yet another DI container -- the Roslyn workspace. This change mostly
represents simplifications and removal of odd dependencies that get us
closer to being able to remove the usage of Roslyn workspace.

I recommend reviewing this commit by commit. Here is a summary of the
changes:

* 7467492a6e70a3b21ef61f59aac391aa9ca93613: I've converted
`ProjectSnapshotManager` to an interface, `IProjectSnapshotManager`.

* c56c2076d64985f01fc3612aae3452d2ada8daad: I clarified the
`IProjectSnapshotManager.GetLoadedProject(...)` API by splitting it into
two:
    * `IProjectSnapshot GetLoadedProject(ProjectKey projectKey)`
Importantly, this marks the return type as non-nullable. Previously, it
returned `IProjectSnapshot?` and callers had to check for null. Now it
throws on null.
* `bool TryGetLoadedProject(ProjectKey projectKey, [NotNullWhen(true)]
out IProjectSnapshot? project)`
      This follows the standard `TryGet*` pattern.

The bulk of this commit is an audit of all callers to
`GetLoadedProject(...)`.

* 550d9a66c31b382c33f2915dba94922f7ef57e5b: I removed the
`ErrorReporter` property from `ProjectSnapshotManagerBase`. There was
really only one case outside of `DefaultProjectSnapshotManager` where
this was used, and I updated that to just import an `IErrorReporter`
directly. (Further work on `IErrorReporter` should be to replace it with
`IRazorLoggerFactory` and friends.)

* 4b04b6a9ab51ca76982c3a4b4c88d4cc98138439: I removed the `Workspace`
property from `ProjectSnapshotManagerBase`. It turns out that some
services were importing `IProjectManagerSnapshotAccessor` just to get at
the `Workspace` property, not because they actually needed to interact
with the `ProjectSnapshotManager`. This is the cause of a few of the
dependency cycles mentioned above. In order to satisfy services needing
to access the Roslyn workspace, I've introduced a new
`IWorkspaceProvider` service that can be imported.

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/ProjectSystem/ProjectSnapshotManagerBenchmarkBase.cs

@@ -6,7 +6,6 @@ using System.Collections.Immutable;
 using System.IO;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.PooledObjects;
-using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;
@@ -60,15 +59,10 @@ public abstract partial class ProjectSnapshotManagerBenchmarkBase
 
     internal DefaultProjectSnapshotManager CreateProjectSnapshotManager()
     {
-        var services = TestServices.Create([], []);
-
         return new DefaultProjectSnapshotManager(
-            new TestErrorReporter(),
             triggers: [],
-#pragma warning disable CA2000 // Dispose objects before losing scope
-            new AdhocWorkspace(services),
-            StaticProjectEngineFactoryProvider.Instance,
-            new TestProjectSnapshotManagerDispatcher());
-#pragma warning restore CA2000 // Dispose objects before losing scope
+            projectEngineFactoryProvider: StaticProjectEngineFactoryProvider.Instance,
+            dispatcher: new TestProjectSnapshotManagerDispatcher(),
+            errorReporter: new TestErrorReporter());
     }
 }

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/CodeDocumentReferenceHolder.cs

@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Razor.LanguageServer;
 internal class CodeDocumentReferenceHolder : DocumentProcessedListener
 {
     private Dictionary<DocumentKey, RazorCodeDocument> _codeDocumentCache;
-    private ProjectSnapshotManager? _projectManager;
+    private IProjectSnapshotManager? _projectManager;
 
     public CodeDocumentReferenceHolder()
     {
@@ -29,7 +29,7 @@ internal class CodeDocumentReferenceHolder : DocumentProcessedListener
         _codeDocumentCache[key] = codeDocument;
     }
 
-    public override void Initialize(ProjectSnapshotManager projectManager)
+    public override void Initialize(IProjectSnapshotManager projectManager)
     {
         _projectManager = projectManager;
         _projectManager.Changed += ProjectManager_Changed;

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/DefaultRazorComponentSearchEngine.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Razor.LanguageServer;
 
 internal class DefaultRazorComponentSearchEngine : RazorComponentSearchEngine
 {
-    private readonly ProjectSnapshotManager _projectSnapshotManager;
+    private readonly IProjectSnapshotManager _projectSnapshotManager;
     private readonly ILogger _logger;
 
     public DefaultRazorComponentSearchEngine(

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Diagnostics/RazorDiagnosticsPublisher.cs

@@ -33,7 +33,7 @@ internal class RazorDiagnosticsPublisher : DocumentProcessedListener
     private readonly IClientConnection _clientConnection;
     private readonly Dictionary<string, IDocumentSnapshot> _work;
     private readonly ILogger _logger;
-    private ProjectSnapshotManager? _projectManager;
+    private IProjectSnapshotManager? _projectManager;
     private readonly LanguageServerFeatureOptions _languageServerFeatureOptions;
     private readonly Lazy<RazorTranslateDiagnosticsService> _razorTranslateDiagnosticsService;
     private readonly Lazy<IDocumentContextFactory> _documentContextFactory;
@@ -93,7 +93,7 @@ internal class RazorDiagnosticsPublisher : DocumentProcessedListener
     // Used in tests to ensure we can control when background work completes.
     public ManualResetEventSlim? NotifyBackgroundWorkCompleting { get; set; }
 
-    public override void Initialize(ProjectSnapshotManager projectManager)
+    public override void Initialize(IProjectSnapshotManager projectManager)
     {
         if (projectManager is null)
         {

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/DocumentContextFactory.cs

@@ -97,8 +97,8 @@ internal sealed class DocumentContextFactory(
             return _snapshotResolver.TryResolveDocumentInAnyProject(filePath, out documentSnapshot);
         }
 
-        var project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectContext.ToProjectKey());
-        if (project?.GetDocument(filePath) is { } document)
+        if (_projectSnapshotManagerAccessor.Instance.TryGetLoadedProject(projectContext.ToProjectKey(), out var project) &&
+            project.GetDocument(filePath) is { } document)
         {
             documentSnapshot = document;
             return true;

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/DocumentProcessedListener.cs

@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Razor.LanguageServer;
 
 internal abstract class DocumentProcessedListener
 {
-    public abstract void Initialize(ProjectSnapshotManager projectManager);
+    public abstract void Initialize(IProjectSnapshotManager projectManager);
 
     public abstract void DocumentProcessed(RazorCodeDocument codeDocument, IDocumentSnapshot documentSnapshot);
 }

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/DocumentVersionCache.cs

@@ -61,8 +61,7 @@ internal sealed partial class DocumentVersionCache() : IDocumentVersionCache, IP
 
         // Any event that has a project may have changed the state of the documents
         // and therefore requires us to mark all existing documents as latest.
-        var project = ProjectSnapshotManager.GetLoadedProject(args.ProjectKey);
-        if (project is null)
+        if (!ProjectSnapshotManager.TryGetLoadedProject(args.ProjectKey, out var project))
         {
             // Project no longer loaded, so there's no work to do.
             return;

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/GeneratedDocumentSynchronizer.cs

@@ -24,7 +24,7 @@ internal class GeneratedDocumentSynchronizer : DocumentProcessedListener
         _dispatcher = dispatcher;
     }
 
-    public override void Initialize(ProjectSnapshotManager projectManager)
+    public override void Initialize(IProjectSnapshotManager projectManager)
     {
     }
 

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/LspProjectSnapshotManagerAccessor.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
-using System;
 using System.Collections.Generic;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
@@ -13,17 +12,14 @@ namespace Microsoft.AspNetCore.Razor.LanguageServer;
 internal sealed class LspProjectSnapshotManagerAccessor(
     IEnumerable<IProjectSnapshotChangeTrigger> changeTriggers,
     IOptionsMonitor<RazorLSPOptions> optionsMonitor,
-    IAdhocWorkspaceFactory workspaceFactory,
     ProjectSnapshotManagerDispatcher dispatcher,
-    IErrorReporter errorReporter) : IProjectSnapshotManagerAccessor, IDisposable
+    IErrorReporter errorReporter) : IProjectSnapshotManagerAccessor
 {
     private readonly IEnumerable<IProjectSnapshotChangeTrigger> _changeTriggers = changeTriggers;
     private readonly IOptionsMonitor<RazorLSPOptions> _optionsMonitor = optionsMonitor;
-    private readonly IAdhocWorkspaceFactory _workspaceFactory = workspaceFactory;
     private readonly ProjectSnapshotManagerDispatcher _dispatcher = dispatcher;
     private readonly IErrorReporter _errorReporter = errorReporter;
     private ProjectSnapshotManagerBase? _instance;
-    private bool _disposed;
 
     public ProjectSnapshotManagerBase Instance
     {
@@ -32,29 +28,15 @@ internal sealed class LspProjectSnapshotManagerAccessor(
             if (_instance is null)
             {
                 var projectEngineFactoryProvider = new LspProjectEngineFactoryProvider(_optionsMonitor);
-                var workspace = _workspaceFactory.Create();
 
                 _instance = new DefaultProjectSnapshotManager(
-                    _errorReporter,
                     _changeTriggers,
-                    workspace,
                     projectEngineFactoryProvider,
-                    _dispatcher);
+                    _dispatcher,
+                    _errorReporter);
             }
 
             return _instance;
         }
     }
-
-    public void Dispose()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-
-        _disposed = true;
-
-        _instance?.Workspace.Dispose();
-    }
 }

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/LspWorkspaceProvider.cs

@@ -0,0 +1,37 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
+
+namespace Microsoft.AspNetCore.Razor.LanguageServer;
+
+internal sealed class LspWorkspaceProvider(IAdhocWorkspaceFactory workspaceFactory) : IWorkspaceProvider, IDisposable
+{
+    private readonly IAdhocWorkspaceFactory _workspaceFactory = workspaceFactory;
+
+    private Workspace? _workspace;
+    private bool _disposed;
+
+    void IDisposable.Dispose()
+    {
+        if (_disposed)
+        {
+            return;
+        }
+
+        _workspace?.Dispose();
+        _disposed = true;
+    }
+
+    public Workspace GetWorkspace()
+    {
+        if (_disposed)
+        {
+            throw new ObjectDisposedException(nameof(LspWorkspaceProvider));
+        }
+
+        return _workspace ??= _workspaceFactory.Create();
+    }
+}

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/ProjectSystem/RazorProjectService.cs

@@ -91,7 +91,7 @@ internal class RazorProjectService(
             // from Misc Project to a real one, and means the newly added document could actually already be open.
             // If it is, we need to make sure we start generating it so we're ready to handle requests that could start coming in.
             if (projectSnapshotManager.IsDocumentOpen(textDocumentPath) &&
-                projectSnapshotManager.GetLoadedProject(projectSnapshot.Key) is { } project &&
+                projectSnapshotManager.TryGetLoadedProject(projectSnapshot.Key, out var project) &&
                 project.GetDocument(textDocumentPath) is { } document)
             {
                 _ = document.GetGeneratedOutputAsync();
@@ -164,7 +164,7 @@ internal class RazorProjectService(
             if (_projectSnapshotManagerAccessor.Instance.IsDocumentOpen(textDocumentPath))
             {
                 _logger.LogInformation("Moving document '{textDocumentPath}' from project '{projectKey}' to misc files because it is open.", textDocumentPath, projectSnapshot.Key);
-                var miscellaneousProject = (ProjectSnapshot)_snapshotResolver.GetMiscellaneousProject();
+                var miscellaneousProject = _snapshotResolver.GetMiscellaneousProject();
                 if (projectSnapshot != miscellaneousProject)
                 {
                     MoveDocument(textDocumentPath, projectSnapshot, miscellaneousProject);
@@ -235,9 +235,7 @@ internal class RazorProjectService(
     {
         _projectSnapshotManagerDispatcher.AssertDispatcherThread();
 
-        var project = (ProjectSnapshot?)_projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectKey);
-
-        if (project is null)
+        if (!_projectSnapshotManagerAccessor.Instance.TryGetLoadedProject(projectKey, out var project))
         {
             // Never tracked the project to begin with, noop.
             _logger.LogInformation("Failed to update untracked project '{projectKey}'.", projectKey);
@@ -254,10 +252,10 @@ internal class RazorProjectService(
 
         _projectSnapshotManagerAccessor.Instance.ProjectWorkspaceStateChanged(project.Key, projectWorkspaceState);
 
-        var currentHostProject = project.HostProject;
-        var currentConfiguration = currentHostProject.Configuration;
+        var currentConfiguration = project.Configuration;
+        var currentRootNamespace = project.RootNamespace;
         if (currentConfiguration.ConfigurationName == configuration?.ConfigurationName &&
-            currentHostProject.RootNamespace == rootNamespace)
+            currentRootNamespace == rootNamespace)
         {
             _logger.LogTrace("Updating project '{key}'. The project is already using configuration '{configuration.ConfigurationName}' and root namespace '{rootNamespace}'.",
                 project.Key, configuration.ConfigurationName, rootNamespace);
@@ -275,7 +273,7 @@ internal class RazorProjectService(
                 project.Key, configuration.ConfigurationName, configuration.LanguageVersion);
         }
 
-        if (currentHostProject.RootNamespace != rootNamespace)
+        if (currentRootNamespace != rootNamespace)
         {
             _logger.LogInformation("Updating project '{key}''s root namespace to '{rootNamespace}'.", project.Key, rootNamespace);
         }
@@ -288,11 +286,11 @@ internal class RazorProjectService(
     {
         _logger.LogDebug("UpdateProjectDocuments for {projectKey} with {documentCount} documents.", projectKey, documents.Length);
 
-        var project = (ProjectSnapshot)_projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectKey).AssumeNotNull();
-        var currentHostProject = project.HostProject;
+        var project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectKey);
+        var currentProjectKey = project.Key;
         var projectDirectory = FilePathNormalizer.GetNormalizedDirectoryName(project.FilePath);
         var documentMap = documents.ToDictionary(document => EnsureFullPath(document.FilePath, projectDirectory), FilePathComparer.Instance);
-        var miscellaneousProject = (ProjectSnapshot)_snapshotResolver.GetMiscellaneousProject();
+        var miscellaneousProject = _snapshotResolver.GetMiscellaneousProject();
 
         // "Remove" any unnecessary documents by putting them into the misc project
         foreach (var documentFilePath in project.DocumentFilePaths)
@@ -308,7 +306,7 @@ internal class RazorProjectService(
             MoveDocument(documentFilePath, project, miscellaneousProject);
         }
 
-        project = (ProjectSnapshot)_projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectKey).AssumeNotNull();
+        project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(projectKey);
 
         // Update existing documents
         foreach (var documentFilePath in project.DocumentFilePaths)
@@ -338,14 +336,14 @@ internal class RazorProjectService(
             _logger.LogTrace("Updating document '{newHostDocument.FilePath}''s file kind to '{newHostDocument.FileKind}' and target path to '{newHostDocument.TargetPath}'.",
                 newHostDocument.FilePath, newHostDocument.FileKind, newHostDocument.TargetPath);
 
-            _projectSnapshotManagerAccessor.Instance.DocumentRemoved(currentHostProject.Key, currentHostDocument);
+            _projectSnapshotManagerAccessor.Instance.DocumentRemoved(currentProjectKey, currentHostDocument);
 
             var remoteTextLoader = _remoteTextLoaderFactory.Create(newFilePath);
-            _projectSnapshotManagerAccessor.Instance.DocumentAdded(currentHostProject.Key, newHostDocument, remoteTextLoader);
+            _projectSnapshotManagerAccessor.Instance.DocumentAdded(currentProjectKey, newHostDocument, remoteTextLoader);
         }
 
-        project = (ProjectSnapshot)_projectSnapshotManagerAccessor.Instance.GetLoadedProject(project.Key).AssumeNotNull();
-        miscellaneousProject = (ProjectSnapshot)_snapshotResolver.GetMiscellaneousProject();
+        project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(project.Key);
+        miscellaneousProject = _snapshotResolver.GetMiscellaneousProject();
 
         // Add (or migrate from misc) any new documents
         foreach (var documentKvp in documentMap)
@@ -367,13 +365,13 @@ internal class RazorProjectService(
                 var remoteTextLoader = _remoteTextLoaderFactory.Create(documentFilePath);
                 var newHostDocument = new HostDocument(documentFilePath, documentHandle.TargetPath, documentHandle.FileKind);
 
-                _logger.LogInformation("Adding new document '{documentFilePath}' to project '{key}'.", documentFilePath, currentHostProject.Key);
-                _projectSnapshotManagerAccessor.Instance.DocumentAdded(currentHostProject.Key, newHostDocument, remoteTextLoader);
+                _logger.LogInformation("Adding new document '{documentFilePath}' to project '{key}'.", documentFilePath, currentProjectKey);
+                _projectSnapshotManagerAccessor.Instance.DocumentAdded(currentProjectKey, newHostDocument, remoteTextLoader);
             }
         }
     }
 
-    private void MoveDocument(string documentFilePath, IProjectSnapshot fromProject, ProjectSnapshot toProject)
+    private void MoveDocument(string documentFilePath, IProjectSnapshot fromProject, IProjectSnapshot toProject)
     {
         Debug.Assert(fromProject.DocumentFilePaths.Contains(documentFilePath, FilePathComparer.Instance));
         Debug.Assert(!toProject.DocumentFilePaths.Contains(documentFilePath, FilePathComparer.Instance));
@@ -424,7 +422,7 @@ internal class RazorProjectService(
                 ?? miscellaneousProject;
 
             var textLoader = new DocumentSnapshotTextLoader(documentSnapshot);
-            var defaultToProject = (ProjectSnapshot)toProject;
+            var defaultToProject = toProject;
             var newHostDocument = new HostDocument(documentSnapshot.FilePath, documentSnapshot.TargetPath, documentSnapshot.FileKind);
 
             _logger.LogInformation("Migrating '{documentFilePath}' from the '{project.Key}' project to '{toProject.KEy}' project.",
@@ -454,13 +452,13 @@ internal class RazorProjectService(
             }
 
             // Remove from miscellaneous project
-            var defaultMiscProject = (ProjectSnapshot)miscellaneousProject;
+            var defaultMiscProject = miscellaneousProject;
             _projectSnapshotManagerAccessor.Instance.DocumentRemoved(defaultMiscProject.Key, documentSnapshot.State.HostDocument);
 
             // Add to new project
 
             var textLoader = new DocumentSnapshotTextLoader(documentSnapshot);
-            var defaultProject = (ProjectSnapshot)projectSnapshot;
+            var defaultProject = projectSnapshot;
             var newHostDocument = new HostDocument(documentSnapshot.FilePath, documentSnapshot.TargetPath);
             _logger.LogInformation("Migrating '{documentFilePath}' from the '{miscellaneousProject.Key}' project to '{projectSnapshot.Key}' project.",
                 documentFilePath, miscellaneousProject.Key, projectSnapshot.Key);

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/ProjectSystem/SnapshotResolver.cs

@@ -64,11 +64,10 @@ internal sealed class SnapshotResolver : ISnapshotResolver
 
     public IProjectSnapshot GetMiscellaneousProject()
     {
-        var miscellaneousProject = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(MiscellaneousHostProject.Key);
-        if (miscellaneousProject is null)
+        if (!_projectSnapshotManagerAccessor.Instance.TryGetLoadedProject(MiscellaneousHostProject.Key, out var miscellaneousProject))
         {
             _projectSnapshotManagerAccessor.Instance.ProjectAdded(MiscellaneousHostProject);
-            miscellaneousProject = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(MiscellaneousHostProject.Key).AssumeNotNull();
+            miscellaneousProject = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(MiscellaneousHostProject.Key);
         }
 
         return miscellaneousProject;

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/RazorLanguageServer.cs

@@ -118,6 +118,7 @@ internal partial class RazorLanguageServer : AbstractLanguageServer<RazorRequest
         }
 
         services.AddSingleton<IAdhocWorkspaceFactory, AdhocWorkspaceFactory>();
+        services.AddSingleton<IWorkspaceProvider, LspWorkspaceProvider>();
 
         var featureOptions = _featureOptions ?? new DefaultLanguageServerFeatureOptions();
         services.AddSingleton(featureOptions);

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Refactoring/RenameEndpoint.cs

@@ -29,7 +29,7 @@ internal sealed class RenameEndpoint : AbstractRazorDelegatingEndpoint<RenamePar
 {
     private readonly ProjectSnapshotManagerDispatcher _projectSnapshotManagerDispatcher;
     private readonly IDocumentContextFactory _documentContextFactory;
-    private readonly ProjectSnapshotManager _projectSnapshotManager;
+    private readonly IProjectSnapshotManager _projectSnapshotManager;
     private readonly RazorComponentSearchEngine _componentSearchEngine;
     private readonly LanguageServerFeatureOptions _languageServerFeatureOptions;
     private readonly IRazorDocumentMappingService _documentMappingService;

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/DefaultRazorDynamicFileInfoProvider.cs

@@ -28,7 +28,7 @@ internal class DefaultRazorDynamicFileInfoProvider : RazorDynamicFileInfoProvide
     private readonly RazorDocumentServiceProviderFactory _factory;
     private readonly LSPEditorFeatureDetector _lspEditorFeatureDetector;
     private readonly FilePathService _filePathService;
-    private readonly IProjectSnapshotManagerAccessor _projectSnapshotManagerAccessor;
+    private readonly IWorkspaceProvider _workspaceProvider;
     private readonly FallbackProjectManager _fallbackProjectManager;
 
     [ImportingConstructor]
@@ -36,14 +36,14 @@ internal class DefaultRazorDynamicFileInfoProvider : RazorDynamicFileInfoProvide
         RazorDocumentServiceProviderFactory factory,
         LSPEditorFeatureDetector lspEditorFeatureDetector,
         FilePathService filePathService,
-        IProjectSnapshotManagerAccessor projectSnapshotManagerAccessor,
+        IWorkspaceProvider workspaceProvider,
         FallbackProjectManager fallbackProjectManager)
     {
-        _factory = factory ?? throw new ArgumentNullException(nameof(factory));
-        _lspEditorFeatureDetector = lspEditorFeatureDetector ?? throw new ArgumentNullException(nameof(lspEditorFeatureDetector));
-        _filePathService = filePathService ?? throw new ArgumentNullException(nameof(filePathService));
-        _projectSnapshotManagerAccessor = projectSnapshotManagerAccessor ?? throw new ArgumentNullException(nameof(projectSnapshotManagerAccessor));
-        _fallbackProjectManager = fallbackProjectManager ?? throw new ArgumentNullException(nameof(fallbackProjectManager));
+        _factory = factory;
+        _lspEditorFeatureDetector = lspEditorFeatureDetector;
+        _filePathService = filePathService;
+        _workspaceProvider = workspaceProvider;
+        _fallbackProjectManager = fallbackProjectManager;
         _entries = new ConcurrentDictionary<Key, Entry>();
         _createEmptyEntry = (key) => new Entry(CreateEmptyInfo(key));
     }
@@ -329,10 +329,7 @@ internal class DefaultRazorDynamicFileInfoProvider : RazorDynamicFileInfoProvide
 
     private ProjectId? TryFindProjectIdForProjectKey(ProjectKey key)
     {
-        if (_projectSnapshotManagerAccessor.Instance.Workspace is not { } workspace)
-        {
-            throw new InvalidOperationException("Can not map a ProjectKey to a ProjectId before the project is initialized");
-        }
+        var workspace = _workspaceProvider.GetWorkspace();
 
         foreach (var project in workspace.CurrentSolution.Projects)
         {
@@ -347,10 +344,7 @@ internal class DefaultRazorDynamicFileInfoProvider : RazorDynamicFileInfoProvide
 
     public ProjectKey? TryFindProjectKeyForProjectId(ProjectId projectId)
     {
-        if (_projectSnapshotManagerAccessor.Instance.Workspace is not { } workspace)
-        {
-            throw new InvalidOperationException("Can not map a ProjectId to a ProjectKey before the project is initialized");
-        }
+        var workspace = _workspaceProvider.GetWorkspace();
 
         var project = workspace.CurrentSolution.GetProject(projectId);
         if (project is null ||

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/IWorkspaceProvider.cs

@@ -0,0 +1,9 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+namespace Microsoft.CodeAnalysis.Razor.Workspaces;
+
+internal interface IWorkspaceProvider
+{
+    Workspace GetWorkspace();
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/DefaultProjectSnapshotManager.cs

@@ -37,19 +37,18 @@ internal class DefaultProjectSnapshotManager : ProjectSnapshotManagerBase
     // We have a queue for changes because if one change results in another change aka, add -> open we want to make sure the "add" finishes running first before "open" is notified.
     private readonly Queue<ProjectChangeEventArgs> _notificationWork = new();
     private readonly IProjectEngineFactoryProvider _projectEngineFactoryProvider;
+    private readonly IErrorReporter _errorReporter;
     private readonly ProjectSnapshotManagerDispatcher _dispatcher;
 
     public DefaultProjectSnapshotManager(
-        IErrorReporter errorReporter,
         IEnumerable<IProjectSnapshotChangeTrigger> triggers,
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider,
-        ProjectSnapshotManagerDispatcher dispatcher)
+        ProjectSnapshotManagerDispatcher dispatcher,
+        IErrorReporter errorReporter)
     {
-        ErrorReporter = errorReporter ?? throw new ArgumentNullException(nameof(errorReporter));
-        Workspace = workspace ?? throw new ArgumentNullException(nameof(workspace));
-        _projectEngineFactoryProvider = projectEngineFactoryProvider ?? throw new ArgumentNullException(nameof(projectEngineFactoryProvider));
-        _dispatcher = dispatcher ?? throw new ArgumentException(nameof(dispatcher));
+        _projectEngineFactoryProvider = projectEngineFactoryProvider;
+        _dispatcher = dispatcher;
+        _errorReporter = errorReporter;
 
         using (_rwLocker.EnterReadLock())
         {
@@ -93,19 +92,32 @@ internal class DefaultProjectSnapshotManager : ProjectSnapshotManagerBase
         return _openDocuments_needsLock.ToImmutableArray();
     }
 
-    internal override Workspace Workspace { get; }
-
-    internal override IErrorReporter ErrorReporter { get; }
-
-    public override IProjectSnapshot? GetLoadedProject(ProjectKey projectKey)
+    public override IProjectSnapshot GetLoadedProject(ProjectKey projectKey)
     {
-        using var _ = _rwLocker.EnterReadLock();
-        if (_projects_needsLock.TryGetValue(projectKey, out var entry))
+        using (_rwLocker.EnterReadLock())
         {
-            return entry.GetSnapshot();
+            if (_projects_needsLock.TryGetValue(projectKey, out var entry))
+            {
+                return entry.GetSnapshot();
+            }
         }
 
-        return null;
+        throw new InvalidOperationException($"No project snapshot exists with the key, '{projectKey}'");
+    }
+
+    public override bool TryGetLoadedProject(ProjectKey projectKey, [NotNullWhen(true)] out IProjectSnapshot? project)
+    {
+        using (_rwLocker.EnterReadLock())
+        {
+            if (_projects_needsLock.TryGetValue(projectKey, out var entry))
+            {
+                project = entry.GetSnapshot();
+                return true;
+            }
+        }
+
+        project = null;
+        return false;
     }
 
     public override ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName)
@@ -347,33 +359,24 @@ internal class DefaultProjectSnapshotManager : ProjectSnapshotManagerBase
 
     internal override void ReportError(Exception exception)
     {
-        if (exception is null)
-        {
-            throw new ArgumentNullException(nameof(exception));
-        }
-
-        ErrorReporter.ReportError(exception);
+        _errorReporter.ReportError(exception);
     }
 
     internal override void ReportError(Exception exception, IProjectSnapshot project)
     {
-        if (exception is null)
-        {
-            throw new ArgumentNullException(nameof(exception));
-        }
-
-        ErrorReporter.ReportError(exception, project);
+        _errorReporter.ReportError(exception, project);
     }
 
     internal override void ReportError(Exception exception, ProjectKey projectKey)
     {
-        if (exception is null)
+        if (TryGetLoadedProject(projectKey, out var project))
         {
-            throw new ArgumentNullException(nameof(exception));
+            _errorReporter.ReportError(exception, project);
+        }
+        else
+        {
+            _errorReporter.ReportError(exception);
         }
-
-        var snapshot = GetLoadedProject(projectKey);
-        ErrorReporter.ReportError(exception, snapshot);
     }
 
     private void NotifyListeners(IProjectSnapshot? older, IProjectSnapshot? newer, string? documentFilePath, ProjectChangeKind kind)

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/DefaultProjectSnapshotManagerFactory.cs

@@ -10,7 +10,7 @@ using Microsoft.CodeAnalysis.Host.Mef;
 namespace Microsoft.CodeAnalysis.Razor.ProjectSystem;
 
 [Shared]
-[ExportLanguageServiceFactory(typeof(ProjectSnapshotManager), RazorLanguage.Name)]
+[ExportLanguageServiceFactory(typeof(IProjectSnapshotManager), RazorLanguage.Name)]
 [method: ImportingConstructor]
 internal class DefaultProjectSnapshotManagerFactory(
     [ImportMany] IEnumerable<IProjectSnapshotChangeTrigger> triggers,
@@ -20,9 +20,8 @@ internal class DefaultProjectSnapshotManagerFactory(
 {
     public ILanguageService CreateLanguageService(HostLanguageServices languageServices)
         => new DefaultProjectSnapshotManager(
-            errorReporter,
             triggers,
-            languageServices.WorkspaceServices.Workspace,
             projectEngineFactoryProvider,
-            dispatcher);
+            dispatcher,
+            errorReporter);
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/FallbackProjectManager.cs

@@ -22,25 +22,29 @@ internal sealed class FallbackProjectManager(
     ProjectConfigurationFilePathStore projectConfigurationFilePathStore,
     LanguageServerFeatureOptions languageServerFeatureOptions,
     IProjectSnapshotManagerAccessor projectSnapshotManagerAccessor,
+    IWorkspaceProvider workspaceProvider,
     ITelemetryReporter telemetryReporter)
 {
     private readonly ProjectConfigurationFilePathStore _projectConfigurationFilePathStore = projectConfigurationFilePathStore;
     private readonly LanguageServerFeatureOptions _languageServerFeatureOptions = languageServerFeatureOptions;
     private readonly IProjectSnapshotManagerAccessor _projectSnapshotManagerAccessor = projectSnapshotManagerAccessor;
+    private readonly IWorkspaceProvider _workspaceProvider = workspaceProvider;
     private readonly ITelemetryReporter _telemetryReporter = telemetryReporter;
 
     internal void DynamicFileAdded(ProjectId projectId, ProjectKey razorProjectKey, string projectFilePath, string filePath)
     {
         try
         {
-            var project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(razorProjectKey);
-            if (project is ProjectSnapshot { HostProject: FallbackHostProject })
+            if (_projectSnapshotManagerAccessor.Instance.TryGetLoadedProject(razorProjectKey, out var project))
             {
-                // If this is a fallback project, then Roslyn may not track documents in the project, so these dynamic file notifications
-                // are the only way to know about files in the project.
-                AddFallbackDocument(razorProjectKey, filePath, projectFilePath);
+                if (project is ProjectSnapshot { HostProject: FallbackHostProject })
+                {
+                    // If this is a fallback project, then Roslyn may not track documents in the project, so these dynamic file notifications
+                    // are the only way to know about files in the project.
+                    AddFallbackDocument(razorProjectKey, filePath, projectFilePath);
+                }
             }
-            else if (project is null)
+            else
             {
                 // We have been asked to provide dynamic file info, which means there is a .razor or .cshtml file in the project
                 // but for some reason our project system doesn't know about the project. In these cases (often when people don't
@@ -58,8 +62,8 @@ internal sealed class FallbackProjectManager(
     {
         try
         {
-            var project = _projectSnapshotManagerAccessor.Instance.GetLoadedProject(razorProjectKey);
-            if (project is ProjectSnapshot { HostProject: FallbackHostProject })
+            if (_projectSnapshotManagerAccessor.Instance.TryGetLoadedProject(razorProjectKey, out var project) &&
+                project is ProjectSnapshot { HostProject: FallbackHostProject })
             {
                 // If this is a fallback project, then Roslyn may not track documents in the project, so these dynamic file notifications
                 // are the only way to know about files in the project.
@@ -156,10 +160,7 @@ internal sealed class FallbackProjectManager(
 
     private Project? TryFindProjectForProjectId(ProjectId projectId)
     {
-        if (_projectSnapshotManagerAccessor.Instance.Workspace is not { } workspace)
-        {
-            throw new InvalidOperationException("Can not map a ProjectId to a ProjectKey before the project is initialized");
-        }
+        var workspace = _workspaceProvider.GetWorkspace();
 
         var project = workspace.CurrentSolution.GetProject(projectId);
         if (project is null ||

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/IProjectSnapshotManager.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis.Host;
+
+namespace Microsoft.CodeAnalysis.Razor.ProjectSystem;
+
+internal interface IProjectSnapshotManager : ILanguageService
+{
+    event EventHandler<ProjectChangeEventArgs> Changed;
+
+    ImmutableArray<IProjectSnapshot> GetProjects();
+
+    bool IsDocumentOpen(string documentFilePath);
+
+    IProjectSnapshot GetLoadedProject(ProjectKey projectKey);
+    bool TryGetLoadedProject(ProjectKey projectKey, [NotNullWhen(true)] out IProjectSnapshot? project);
+
+    ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName);
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/ProjectSnapshotManager.cs

@@ -1,21 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
-
-using System;
-using System.Collections.Immutable;
-using Microsoft.CodeAnalysis.Host;
-
-namespace Microsoft.CodeAnalysis.Razor.ProjectSystem;
-
-internal abstract class ProjectSnapshotManager : ILanguageService
-{
-    public abstract event EventHandler<ProjectChangeEventArgs> Changed;
-
-    public abstract ImmutableArray<IProjectSnapshot> GetProjects();
-
-    public abstract bool IsDocumentOpen(string documentFilePath);
-
-    public abstract IProjectSnapshot? GetLoadedProject(ProjectKey projectKey);
-
-    public abstract ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName);
-}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/ProjectSnapshotManagerBase.cs

@@ -3,16 +3,25 @@
 
 using System;
 using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;
 
 namespace Microsoft.CodeAnalysis.Razor.ProjectSystem;
 
-internal abstract class ProjectSnapshotManagerBase : ProjectSnapshotManager
+internal abstract class ProjectSnapshotManagerBase : IProjectSnapshotManager
 {
-    internal abstract Workspace Workspace { get; }
+    public abstract event EventHandler<ProjectChangeEventArgs> Changed;
 
-    internal abstract IErrorReporter ErrorReporter { get; }
+    public abstract ImmutableArray<IProjectSnapshot> GetProjects();
+
+    public abstract bool IsDocumentOpen(string documentFilePath);
+
+    public abstract IProjectSnapshot GetLoadedProject(ProjectKey projectKey);
+
+    public abstract bool TryGetLoadedProject(ProjectKey projectKey, [NotNullWhen(true)] out IProjectSnapshot? project);
+
+    public abstract ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName);
 
     internal abstract ImmutableArray<string> GetOpenDocuments();
 

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/ProjectSystem/WorkspaceProjectStateChangeDetector.cs

@@ -24,8 +24,10 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
     private readonly object _disposedLock = new();
     private readonly object _workQueueAccessLock = new();
     private readonly IProjectWorkspaceStateGenerator _workspaceStateGenerator;
-    private readonly ProjectSnapshotManagerDispatcher _dispatcher;
     private readonly LanguageServerFeatureOptions _options;
+    private readonly IWorkspaceProvider _workspaceProvider;
+    private readonly ProjectSnapshotManagerDispatcher _dispatcher;
+    private readonly IErrorReporter _errorReporter;
     private BatchingWorkQueue? _workQueue;
     private ProjectSnapshotManagerBase? _projectManager;
     private bool _disposed;
@@ -36,24 +38,28 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
     [ImportingConstructor]
     public WorkspaceProjectStateChangeDetector(
         IProjectWorkspaceStateGenerator workspaceStateGenerator,
+        LanguageServerFeatureOptions options,
+        IWorkspaceProvider workspaceProvider,
         ProjectSnapshotManagerDispatcher dispatcher,
-        LanguageServerFeatureOptions options)
+        IErrorReporter errorReporter)
     {
-        _workspaceStateGenerator = workspaceStateGenerator ?? throw new ArgumentNullException(nameof(workspaceStateGenerator));
-        _dispatcher = dispatcher ?? throw new ArgumentNullException(nameof(dispatcher));
-        _options = options ?? throw new ArgumentNullException(nameof(options));
+        _workspaceStateGenerator = workspaceStateGenerator;
+        _options = options;
+        _workspaceProvider = workspaceProvider;
+        _dispatcher = dispatcher;
+        _errorReporter = errorReporter;
     }
 
     // Internal for testing
     internal WorkspaceProjectStateChangeDetector(
         IProjectWorkspaceStateGenerator workspaceStateGenerator,
-        ProjectSnapshotManagerDispatcher dispatcher,
         LanguageServerFeatureOptions options,
+        IWorkspaceProvider workspaceProvider,
+        IErrorReporter errorReporter,
+        ProjectSnapshotManagerDispatcher dispatcher,
         BatchingWorkQueue workQueue)
+        : this(workspaceStateGenerator, options, workspaceProvider, dispatcher, errorReporter)
     {
-        _workspaceStateGenerator = workspaceStateGenerator;
-        _dispatcher = dispatcher;
-        _options = options;
         _workQueue = workQueue;
     }
 
@@ -66,11 +72,13 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
         EnsureWorkQueue();
 
         projectManager.Changed += ProjectManager_Changed;
-        projectManager.Workspace.WorkspaceChanged += Workspace_WorkspaceChanged;
+
+        var workspace = _workspaceProvider.GetWorkspace();
+        workspace.WorkspaceChanged += Workspace_WorkspaceChanged;
 
         // This will usually no-op, in the case that another project snapshot change trigger
         // immediately adds projects we want to be able to handle those projects.
-        InitializeSolution(projectManager.Workspace.CurrentSolution);
+        InitializeSolution(workspace.CurrentSolution);
     }
 
     private void EnsureWorkQueue()
@@ -87,7 +95,7 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
                 _workQueue ??= new BatchingWorkQueue(
                     s_batchingDelay,
                     FilePathComparer.Instance,
-                    projectManager.ErrorReporter);
+                    _errorReporter);
             }
         }
     }
@@ -412,7 +420,8 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
             case ProjectChangeKind.ProjectAdded:
             case ProjectChangeKind.DocumentRemoved:
             case ProjectChangeKind.DocumentAdded:
-                var currentSolution = ProjectSnapshotManager.Workspace.CurrentSolution;
+                var workspace = _workspaceProvider.GetWorkspace();
+                var currentSolution = workspace.CurrentSolution;
                 var associatedWorkspaceProject = currentSolution.Projects
                     .FirstOrDefault(project => e.ProjectKey == ProjectKey.From(project));
 
@@ -483,8 +492,7 @@ internal class WorkspaceProjectStateChangeDetector : IProjectSnapshotChangeTrigg
             return false;
         }
 
-        projectSnapshot = ProjectSnapshotManager.GetLoadedProject(projectKey);
-        return projectSnapshot is not null;
+        return ProjectSnapshotManager.TryGetLoadedProject(projectKey, out projectSnapshot);
     }
 
     public void Dispose()

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/OutOfProcTagHelperResolver.cs

@@ -22,11 +22,11 @@ namespace Microsoft.CodeAnalysis.Remote.Razor;
 [Export(typeof(ITagHelperResolver))]
 [method: ImportingConstructor]
 internal class OutOfProcTagHelperResolver(
-    IProjectSnapshotManagerAccessor projectManagerAccessor,
+    IWorkspaceProvider workspaceProvider,
     IErrorReporter errorReporter,
     ITelemetryReporter telemetryReporter) : ITagHelperResolver
 {
-    private readonly IProjectSnapshotManagerAccessor _projectManagerAccessor = projectManagerAccessor;
+    private readonly IWorkspaceProvider _workspaceProvider = workspaceProvider;
     private readonly IErrorReporter _errorReporter = errorReporter;
     private readonly CompilationTagHelperResolver _innerResolver = new(telemetryReporter);
     private readonly TagHelperResultCache _resultCache = new();
@@ -71,8 +71,10 @@ internal class OutOfProcTagHelperResolver(
         // when it's disconnected (user stops the process).
         //
         // This will change in the future to an easier to consume API but for VS RTM this is what we have.
+        var workspace = _workspaceProvider.GetWorkspace();
+
         var remoteClient = await RazorRemoteHostClient.TryGetClientAsync(
-            _projectManagerAccessor.Instance.Workspace.Services,
+            workspace.Services,
             RazorServiceDescriptors.TagHelperProviderServiceDescriptors,
             RazorRemoteServiceCallbackDispatcherRegistry.Empty,
             cancellationToken);

src/Razor/src/Microsoft.VisualStudio.Editor.Razor/DefaultVisualStudioDocumentTracker.cs

@@ -8,7 +8,6 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
-using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.Editor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
@@ -190,15 +189,16 @@ internal class DefaultVisualStudioDocumentTracker : VisualStudioDocumentTracker
         _ = OnContextChangedAsync(ContextChangeKind.ProjectChanged);
     }
 
-    private IProjectSnapshot? GetOrCreateProject(string projectPath)
+    private IProjectSnapshot GetOrCreateProject(string projectPath)
     {
         _dispatcher.AssertDispatcherThread();
 
         var projectManager = _projectManagerAccessor.Instance;
 
-        var projectKey = projectManager.GetAllProjectKeys(projectPath).FirstOrDefault();
+        var projectKeys = projectManager.GetAllProjectKeys(projectPath);
 
-        if (projectManager.GetLoadedProject(projectKey) is not { } project)
+        if (projectKeys.Length == 0 ||
+            !projectManager.TryGetLoadedProject(projectKeys[0], out var project))
         {
             return new EphemeralProjectSnapshot(_projectEngineFactoryProvider, projectPath);
         }
@@ -249,7 +249,10 @@ internal class DefaultVisualStudioDocumentTracker : VisualStudioDocumentTracker
             string.Equals(_projectPath, e.ProjectFilePath, StringComparison.OrdinalIgnoreCase))
         {
             // This will be the new snapshot unless the project was removed.
-            _projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(e.ProjectKey);
+            if (!_projectManagerAccessor.Instance.TryGetLoadedProject(e.ProjectKey, out _projectSnapshot))
+            {
+                _projectSnapshot = null;
+            }
 
             switch (e.Kind)
             {

src/Razor/src/Microsoft.VisualStudio.Editor.Razor/Documents/EditorDocumentManagerListener.cs

@@ -11,6 +11,7 @@ using Microsoft.AspNetCore.Razor;
 using Microsoft.AspNetCore.Razor.Telemetry;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.VisualStudio.Threading;
 
 namespace Microsoft.VisualStudio.Editor.Razor.Documents;
@@ -28,7 +29,8 @@ namespace Microsoft.VisualStudio.Editor.Razor.Documents;
 [Export(typeof(IProjectSnapshotChangeTrigger))]
 internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTrigger
 {
-    private readonly ProjectSnapshotManagerDispatcher _projectSnapshotManagerDispatcher;
+    private readonly IWorkspaceProvider _workspaceProvider;
+    private readonly ProjectSnapshotManagerDispatcher _dispatcher;
     private readonly JoinableTaskContext _joinableTaskContext;
     private readonly ITelemetryReporter _telemetryReporter;
     private readonly EventHandler? _onChangedOnDisk;
@@ -43,11 +45,16 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
     public ProjectSnapshotManagerBase ProjectManager => _projectManager ?? throw new InvalidOperationException($"{nameof(ProjectManager)} called before {nameof(Initialize)}");
 
     [ImportingConstructor]
-    public EditorDocumentManagerListener(ProjectSnapshotManagerDispatcher projectSnapshotManagerDispatcher, JoinableTaskContext joinableTaskContext, ITelemetryReporter telemetryReporter)
+    public EditorDocumentManagerListener(
+        IWorkspaceProvider workspaceProvider,
+        ProjectSnapshotManagerDispatcher dispatcher,
+        JoinableTaskContext joinableTaskContext,
+        ITelemetryReporter telemetryReporter)
     {
-        _projectSnapshotManagerDispatcher = projectSnapshotManagerDispatcher ?? throw new ArgumentNullException(nameof(projectSnapshotManagerDispatcher));
-        _joinableTaskContext = joinableTaskContext ?? throw new ArgumentNullException(nameof(joinableTaskContext));
-        _telemetryReporter = telemetryReporter ?? throw new ArgumentNullException(nameof(telemetryReporter));
+        _workspaceProvider = workspaceProvider;
+        _dispatcher = dispatcher;
+        _joinableTaskContext = joinableTaskContext;
+        _telemetryReporter = telemetryReporter;
 
         _onChangedOnDisk = Document_ChangedOnDisk;
         _onChangedInEditor = Document_ChangedInEditor;
@@ -57,7 +64,8 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
 
     // For testing purposes only.
     internal EditorDocumentManagerListener(
-        ProjectSnapshotManagerDispatcher projectSnapshotManagerDispatcher,
+        IWorkspaceProvider workspaceProvider,
+        ProjectSnapshotManagerDispatcher dispatcher,
         JoinableTaskContext joinableTaskContext,
         EditorDocumentManager documentManager,
         EventHandler? onChangedOnDisk,
@@ -65,7 +73,8 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
         EventHandler onOpened,
         EventHandler? onClosed)
     {
-        _projectSnapshotManagerDispatcher = projectSnapshotManagerDispatcher;
+        _workspaceProvider = workspaceProvider;
+        _dispatcher = dispatcher;
         _joinableTaskContext = joinableTaskContext;
         _documentManager = documentManager;
         _onChangedOnDisk = onChangedOnDisk;
@@ -80,7 +89,9 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
     public void Initialize(ProjectSnapshotManagerBase projectManager)
     {
         _projectManager = projectManager;
-        _documentManager = projectManager.Workspace.Services.GetRequiredService<EditorDocumentManager>();
+
+        var workspace = _workspaceProvider.GetWorkspace();
+        _documentManager = workspace.Services.GetRequiredService<EditorDocumentManager>();
 
         _projectManager.Changed += ProjectManager_Changed;
     }
@@ -174,7 +185,7 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
             // This event is called by the EditorDocumentManager, which runs on the UI thread.
             // However, due to accessing the project snapshot manager, we need to switch to
             // running on the project snapshot manager's specialized thread.
-            await _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(() =>
+            await _dispatcher.RunOnDispatcherThreadAsync(() =>
             {
                 ProjectManager.DocumentChanged(document.ProjectKey, document.DocumentFilePath, document.TextLoader);
             }, cancellationToken).ConfigureAwait(false);
@@ -202,7 +213,7 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
             // This event is called by the EditorDocumentManager, which runs on the UI thread.
             // However, due to accessing the project snapshot manager, we need to switch to
             // running on the project snapshot manager's specialized thread.
-            await _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(() =>
+            await _dispatcher.RunOnDispatcherThreadAsync(() =>
             {
                 var document = (EditorDocument)sender;
                 ProjectManager.DocumentChanged(document.ProjectKey, document.DocumentFilePath, document.EditorTextContainer!.CurrentText);
@@ -232,12 +243,12 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
             // This event is called by the EditorDocumentManager, which runs on the UI thread.
             // However, due to accessing the project snapshot manager, we need to switch to
             // running on the project snapshot manager's specialized thread.
-            await _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(() =>
+            await _dispatcher.RunOnDispatcherThreadAsync(() =>
             {
                 var document = (EditorDocument)sender;
 
-                var project = ProjectManager.GetLoadedProject(document.ProjectKey);
-                if (project is ProjectSnapshot { HostProject: FallbackHostProject } projectSnapshot)
+                if (ProjectManager.TryGetLoadedProject(document.ProjectKey, out var project) &&
+                    project is ProjectSnapshot { HostProject: FallbackHostProject } projectSnapshot)
                 {
                     // The user is opening a document that is part of a fallback project. This is a scenario we are very interested in knowing more about
                     // so fire some telemetry. We can't log details about the project, for PII reasons, but we can use document count and tag helper count
@@ -275,7 +286,7 @@ internal class EditorDocumentManagerListener : IPriorityProjectSnapshotChangeTri
             // This event is called by the EditorDocumentManager, which runs on the UI thread.
             // However, due to accessing the project snapshot manager, we need to switch to
             // running on the project snapshot manager's specialized thread.
-            await _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(() =>
+            await _dispatcher.RunOnDispatcherThreadAsync(() =>
             {
                 var document = (EditorDocument)sender;
                 ProjectManager.DocumentClosed(document.ProjectKey, document.DocumentFilePath, document.TextLoader);

src/Razor/src/Microsoft.VisualStudio.Editor.Razor/Documents/RazorCodeDocumentProvidingSnapshotChangeTrigger.cs

@@ -77,7 +77,18 @@ internal class RazorCodeDocumentProvidingSnapshotChangeTrigger : IProjectSnapsho
         }
 
         var project = await _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(
-            () => _projectManager?.GetLoadedProject(projectKey), cancellationToken);
+            () =>
+            {
+                if (_projectManager is { } projectManager &&
+                    projectManager.TryGetLoadedProject(projectKey, out var project))
+                {
+                    return project;
+                }
+                else
+                {
+                    return null;
+                }
+            }, cancellationToken);
 
         if (project is null)
         {

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/ProjectSystem/WindowsRazorProjectHostBase.cs

@@ -231,8 +231,7 @@ internal abstract class WindowsRazorProjectHostBase : OnceInitializedOnceDispose
             var projectKeys = projectManager.GetAllProjectKeys(oldProjectFilePath);
             foreach (var projectKey in projectKeys)
             {
-                var current = projectManager.GetLoadedProject(projectKey);
-                if (current?.Configuration is not null)
+                if (projectManager.TryGetLoadedProject(projectKey, out var current))
                 {
                     UninitializeProjectUnsafe(projectKey);
 
@@ -268,8 +267,7 @@ internal abstract class WindowsRazorProjectHostBase : OnceInitializedOnceDispose
     protected void UninitializeProjectUnsafe(ProjectKey projectKey)
     {
         var projectManager = GetProjectManager();
-        var current = projectManager.GetLoadedProject(projectKey);
-        if (current is not null)
+        if (projectManager.TryGetLoadedProject(projectKey, out _))
         {
             projectManager.ProjectRemoved(projectKey);
             ProjectConfigurationFilePathStore.Remove(projectKey);
@@ -280,8 +278,7 @@ internal abstract class WindowsRazorProjectHostBase : OnceInitializedOnceDispose
     {
         var projectManager = GetProjectManager();
 
-        var current = projectManager.GetLoadedProject(project.Key);
-        if (current is null)
+        if (!projectManager.TryGetLoadedProject(project.Key, out _))
         {
             // Just in case we somehow got in a state where VS didn't tell us that solution close was finished, lets just
             // ensure we're going to actually do something with the new project that we've just been told about.

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/VisualStudioProjectSnapshotManagerAccessor.cs

@@ -56,7 +56,7 @@ internal sealed class VisualStudioProjectSnapshotManagerAccessor(
 
                 return (ProjectSnapshotManagerBase)_workspace.Services
                     .GetLanguageServices(RazorLanguage.Name)
-                    .GetRequiredService<ProjectSnapshotManager>();
+                    .GetRequiredService<IProjectSnapshotManager>();
             }
         }
     }

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/VisualStudioWorkspaceProvider.cs

@@ -0,0 +1,15 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.ComponentModel.Composition;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
+
+namespace Microsoft.VisualStudio.LanguageServices.Razor;
+
+[Export(typeof(IWorkspaceProvider))]
+[method: ImportingConstructor]
+internal sealed class VisualStudioWorkspaceProvider(VisualStudioWorkspace workspace) : IWorkspaceProvider
+{
+    public Workspace GetWorkspace() => workspace;
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/VsSolutionUpdatesProjectSnapshotChangeTrigger.cs

@@ -9,6 +9,7 @@ using System.Runtime.InteropServices;
 using System.Threading;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.VisualStudio.Editor.Razor;
 using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Shell.Interop;
@@ -18,59 +19,27 @@ using Task = System.Threading.Tasks.Task;
 namespace Microsoft.VisualStudio.LanguageServices.Razor;
 
 [Export(typeof(IProjectSnapshotChangeTrigger))]
-internal class VsSolutionUpdatesProjectSnapshotChangeTrigger : IProjectSnapshotChangeTrigger, IVsUpdateSolutionEvents2, IDisposable
+[method: ImportingConstructor]
+internal class VsSolutionUpdatesProjectSnapshotChangeTrigger(
+    [Import(typeof(SVsServiceProvider))] IServiceProvider services,
+    TextBufferProjectService projectService,
+    IProjectWorkspaceStateGenerator workspaceStateGenerator,
+    IWorkspaceProvider workspaceProvider,
+    ProjectSnapshotManagerDispatcher dispatcher,
+    JoinableTaskContext joinableTaskContext) : IProjectSnapshotChangeTrigger, IVsUpdateSolutionEvents2, IDisposable
 {
-    private readonly IServiceProvider _services;
-    private readonly TextBufferProjectService _projectService;
-    private readonly IProjectWorkspaceStateGenerator _workspaceStateGenerator;
-    private readonly ProjectSnapshotManagerDispatcher _projectSnapshotManagerDispatcher;
-    private readonly JoinableTaskContext _joinableTaskContext;
+    private readonly IServiceProvider _services = services;
+    private readonly TextBufferProjectService _projectService = projectService;
+    private readonly IProjectWorkspaceStateGenerator _workspaceStateGenerator = workspaceStateGenerator;
+    private readonly IWorkspaceProvider _workspaceProvider = workspaceProvider;
+    private readonly ProjectSnapshotManagerDispatcher _dispatcher = dispatcher;
+    private readonly JoinableTaskContext _joinableTaskContext = joinableTaskContext;
+
     private ProjectSnapshotManagerBase? _projectManager;
-    private CancellationTokenSource? _activeSolutionCancellationTokenSource;
+    private CancellationTokenSource? _activeSolutionCancellationTokenSource = new();
     private uint _updateCookie;
     private IVsSolutionBuildManager? _solutionBuildManager;
 
-    [ImportingConstructor]
-    public VsSolutionUpdatesProjectSnapshotChangeTrigger(
-        [Import(typeof(SVsServiceProvider))] IServiceProvider services,
-        TextBufferProjectService projectService,
-        IProjectWorkspaceStateGenerator workspaceStateGenerator,
-        ProjectSnapshotManagerDispatcher projectSnapshotManagerDispatcher,
-        JoinableTaskContext joinableTaskContext)
-    {
-        if (services is null)
-        {
-            throw new ArgumentNullException(nameof(services));
-        }
-
-        if (projectService is null)
-        {
-            throw new ArgumentNullException(nameof(projectService));
-        }
-
-        if (workspaceStateGenerator is null)
-        {
-            throw new ArgumentNullException(nameof(workspaceStateGenerator));
-        }
-
-        if (projectSnapshotManagerDispatcher is null)
-        {
-            throw new ArgumentNullException(nameof(projectSnapshotManagerDispatcher));
-        }
-
-        if (joinableTaskContext is null)
-        {
-            throw new ArgumentNullException(nameof(joinableTaskContext));
-        }
-
-        _services = services;
-        _projectService = projectService;
-        _workspaceStateGenerator = workspaceStateGenerator;
-        _projectSnapshotManagerDispatcher = projectSnapshotManagerDispatcher;
-        _joinableTaskContext = joinableTaskContext;
-        _activeSolutionCancellationTokenSource = new CancellationTokenSource();
-    }
-
     internal Task? CurrentUpdateTaskForTests { get; private set; }
 
     public void Initialize(ProjectSnapshotManagerBase projectManager)
@@ -142,7 +111,7 @@ internal class VsSolutionUpdatesProjectSnapshotChangeTrigger : IProjectSnapshotC
     internal Task OnProjectBuiltAsync(IVsHierarchy projectHierarchy, CancellationToken cancellationToken)
     {
         var projectFilePath = _projectService.GetProjectPath(projectHierarchy);
-        return _projectSnapshotManagerDispatcher.RunOnDispatcherThreadAsync(() =>
+        return _dispatcher.RunOnDispatcherThreadAsync(() =>
         {
             if (_projectManager is null)
             {
@@ -152,10 +121,10 @@ internal class VsSolutionUpdatesProjectSnapshotChangeTrigger : IProjectSnapshotC
             var projectKeys = _projectManager.GetAllProjectKeys(projectFilePath);
             foreach (var projectKey in projectKeys)
             {
-                var projectSnapshot = _projectManager?.GetLoadedProject(projectKey);
-                if (projectSnapshot is not null)
+                if (_projectManager.TryGetLoadedProject(projectKey, out var projectSnapshot))
                 {
-                    var workspaceProject = _projectManager?.Workspace.CurrentSolution.Projects.FirstOrDefault(wp => ProjectKey.From(wp) == projectSnapshot.Key);
+                    var workspace = _workspaceProvider.GetWorkspace();
+                    var workspaceProject = workspace.CurrentSolution.Projects.FirstOrDefault(wp => ProjectKey.From(wp) == projectSnapshot.Key);
                     if (workspaceProject is not null)
                     {
                         // Trigger a tag helper update by forcing the project manager to see the workspace Project

src/Razor/src/Microsoft.VisualStudio.LiveShare.Razor/Host/DefaultProjectSnapshotManagerProxy.cs

@@ -17,7 +17,7 @@ internal class DefaultProjectSnapshotManagerProxy : IProjectSnapshotManagerProxy
 {
     private readonly CollaborationSession _session;
     private readonly ProjectSnapshotManagerDispatcher _dispatcher;
-    private readonly ProjectSnapshotManager _projectSnapshotManager;
+    private readonly IProjectSnapshotManager _projectSnapshotManager;
     private readonly JoinableTaskFactory _joinableTaskFactory;
     private readonly AsyncSemaphore _latestStateSemaphore;
     private bool _disposed;
@@ -29,7 +29,7 @@ internal class DefaultProjectSnapshotManagerProxy : IProjectSnapshotManagerProxy
     public DefaultProjectSnapshotManagerProxy(
         CollaborationSession session,
         ProjectSnapshotManagerDispatcher dispatcher,
-        ProjectSnapshotManager projectSnapshotManager,
+        IProjectSnapshotManager projectSnapshotManager,
         JoinableTaskFactory joinableTaskFactory)
     {
         if (session is null)

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/CodeDocumentReferenceHolderTest.cs

@@ -25,7 +25,7 @@ public class CodeDocumentReferenceHolderTest : LanguageServerTestBase
     public CodeDocumentReferenceHolderTest(ITestOutputHelper testOutput)
         : base(testOutput)
     {
-        _projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        _projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         _projectManager.AllowNotifyListeners = true;
         _referenceHolder = new CodeDocumentReferenceHolder();
         _referenceHolder.Initialize(_projectManager);
@@ -165,7 +165,7 @@ public class CodeDocumentReferenceHolderTest : LanguageServerTestBase
             _projectManager.ProjectAdded(_hostProject);
             var textLoader = new SourceTextLoader("<p>Hello World</p>", _hostDocument.FilePath);
             _projectManager.DocumentAdded(_hostProject.Key, _hostDocument, textLoader);
-            var project = _projectManager.GetLoadedProject(_hostProject.Key).AssumeNotNull();
+            var project = _projectManager.GetLoadedProject(_hostProject.Key);
             return project.GetDocument(_hostDocument.FilePath).AssumeNotNull();
         }, cancellationToken);
     }

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/DefaultWorkspaceSemanticTokensRefreshTriggerTest.cs

@@ -23,7 +23,7 @@ public class DefaultWorkspaceSemanticTokensRefreshTriggerTest : LanguageServerTe
     public DefaultWorkspaceSemanticTokensRefreshTriggerTest(ITestOutputHelper testOutput)
         : base(testOutput)
     {
-        _projectManager = TestProjectSnapshotManager.Create(ErrorReporter, new TestDispatcher());
+        _projectManager = TestProjectSnapshotManager.Create(new TestDispatcher(), ErrorReporter);
         _projectManager.AllowNotifyListeners = true;
         _hostProject = new HostProject("/path/to/project.csproj", "/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         _projectManager.ProjectAdded(_hostProject);

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Diagnostics/RazorDiagnosticsPublisherTest.cs

@@ -49,7 +49,7 @@ public class RazorDiagnosticsPublisherTest : LanguageServerTestBase
         }
     ];
 
-    private readonly ProjectSnapshotManager _projectManager;
+    private readonly IProjectSnapshotManager _projectManager;
     private readonly IDocumentSnapshot _closedDocument;
     private readonly IDocumentSnapshot _openedDocument;
     private readonly RazorCodeDocument _testCodeDocument;
@@ -58,7 +58,7 @@ public class RazorDiagnosticsPublisherTest : LanguageServerTestBase
     public RazorDiagnosticsPublisherTest(ITestOutputHelper testOutput)
         : base(testOutput)
     {
-        var testProjectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var testProjectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("C:/project/project.csproj", "C:/project/obj", RazorConfiguration.Default, "TestRootNamespace");
         testProjectManager.ProjectAdded(hostProject);
         var sourceText = SourceText.From(string.Empty);

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/DocumentContextFactoryTest.cs

@@ -31,7 +31,7 @@ public class DocumentContextFactoryTest : LanguageServerTestBase
     {
         _documentVersionCache = new DocumentVersionCache();
 
-        _projectSnapshotManagerBase = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        _projectSnapshotManagerBase = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         _projectSnapshotManagerAccessor = new TestProjectSnapshotManagerAccessor(_projectSnapshotManagerBase);
     }
 

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/DocumentVersionCacheTest.cs

@@ -317,7 +317,7 @@ public class DocumentVersionCacheTest(ITestOutputHelper testOutput) : LanguageSe
 
     private TestProjectSnapshotManager CreateProjectSnapshotManager()
     {
-        var result = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var result = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         result.AllowNotifyListeners = true;
 
         return result;

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/GeneratedDocumentPublisherTest.cs

@@ -25,7 +25,7 @@ public class GeneratedDocumentPublisherTest : LanguageServerTestBase
         : base(testOutput)
     {
         _serverClient = new TestClient();
-        _projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        _projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         _projectManager.AllowNotifyListeners = true;
         _hostProject = new HostProject("/path/to/project.csproj", "/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         _hostProject2 = new HostProject("/path/to/project2.csproj", "/path/to/obj2", RazorConfiguration.Default, "TestRootNamespace");

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/OpenDocumentGeneratorTest.cs

@@ -42,7 +42,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
     public async Task DocumentAdded_IgnoresClosedDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var listener = new TestDocumentProcessedListener();
         var queue = new TestOpenDocumentGenerator(Dispatcher, ErrorReporter, listener);
 
@@ -66,7 +66,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
     public async Task DocumentChanged_IgnoresClosedDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var listener = new TestDocumentProcessedListener();
         var queue = new TestOpenDocumentGenerator(Dispatcher, ErrorReporter, listener);
 
@@ -91,7 +91,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
     public async Task DocumentChanged_ProcessesOpenDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var listener = new TestDocumentProcessedListener();
         var queue = new TestOpenDocumentGenerator(Dispatcher, ErrorReporter, listener);
 
@@ -119,7 +119,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
     public async Task ProjectChanged_IgnoresClosedDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var listener = new TestDocumentProcessedListener();
         var queue = new TestOpenDocumentGenerator(Dispatcher, ErrorReporter, listener);
 
@@ -145,7 +145,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
     public async Task ProjectChanged_ProcessesOpenDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var listener = new TestDocumentProcessedListener();
         var queue = new TestOpenDocumentGenerator(Dispatcher, ErrorReporter, listener);
 
@@ -210,7 +210,7 @@ public class OpenDocumentGeneratorTest : LanguageServerTestBase
             _tcs.SetResult(document);
         }
 
-        public override void Initialize(ProjectSnapshotManager projectManager)
+        public override void Initialize(IProjectSnapshotManager projectManager)
         {
         }
     }

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/RazorProjectServiceTest.cs

@@ -34,7 +34,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_UpdatesProjectWorkspaceState()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("C:/path/to/project.csproj", "C:/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(hostProject);
         var projectService = CreateProjectService(new TestSnapshotResolver(), projectManager);
@@ -59,7 +59,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_UpdatingDocument_MapsRelativeFilePathToActualDocument()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("C:/path/to/project.csproj", "C:/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(hostProject);
         var hostDocument = new HostDocument("C:/path/to/file.cshtml", "file.cshtml", FileKinds.Legacy);
@@ -88,7 +88,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_AddsNewDocuments()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("C:/path/to/project.csproj", "C:/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(hostProject);
         var hostDocument = new HostDocument("C:/path/to/file.cshtml", "file.cshtml", FileKinds.Legacy);
@@ -117,7 +117,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_MovesDocumentsFromMisc()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostDocument = new HostDocument("C:/path/to/file.cshtml", "file.cshtml", FileKinds.Legacy);
         var miscProject = TestProjectSnapshot.Create("C:/__MISC_PROJECT__");
         projectManager.ProjectAdded(miscProject.HostProject);
@@ -157,7 +157,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_MovesExistingDocumentToMisc()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         IProjectSnapshot miscProject = TestProjectSnapshot.Create("C:/__MISC_PROJECT__");
         var miscHostProject = new HostProject(miscProject.FilePath, miscProject.IntermediateOutputPath, RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(miscHostProject);
@@ -197,7 +197,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_KnownDocuments()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("path/to/project.csproj", "path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(hostProject);
         var document = new HostDocument("path/to/file.cshtml", "file.cshtml", FileKinds.Legacy);
@@ -230,7 +230,7 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     public async Task UpdateProject_UpdatesLegacyDocumentsAsComponents()
     {
         // Arrange
-        var projectManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var projectManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var hostProject = new HostProject("C:/path/to/project.csproj", "C:/path/to/obj", RazorConfiguration.Default, "TestRootNamespace");
         projectManager.ProjectAdded(hostProject);
         var legacyDocument = new HostDocument("C:/path/to/file.cshtml", "file.cshtml", FileKinds.Legacy);
@@ -260,13 +260,19 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     {
         // Arrange
         var projectFilePath = "C:/path/to/project.csproj";
-        var ownerProject = TestProjectSnapshot.Create(projectFilePath);
+        IProjectSnapshot ownerProject = TestProjectSnapshot.Create(projectFilePath);
         var projectSnapshotManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
         var expectedRootNamespace = "NewRootNamespace";
-        projectSnapshotManager.Setup(manager => manager.GetLoadedProject(ownerProject.Key))
+        projectSnapshotManager
+            .Setup(manager => manager.GetLoadedProject(ownerProject.Key))
             .Returns(ownerProject);
-        projectSnapshotManager.Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
-        projectSnapshotManager.Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
+        projectSnapshotManager
+            .Setup(manager => manager.TryGetLoadedProject(ownerProject.Key, out ownerProject))
+            .Returns(true);
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
             .Callback<HostProject>((hostProject) => Assert.Equal(expectedRootNamespace, hostProject.RootNamespace));
         var projectService = CreateProjectService(new TestSnapshotResolver(), projectSnapshotManager.Object);
 
@@ -289,12 +295,18 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     {
         // Arrange
         var projectFilePath = "C:/path/to/project.csproj";
-        var ownerProject = TestProjectSnapshot.Create(projectFilePath);
+        IProjectSnapshot ownerProject = TestProjectSnapshot.Create(projectFilePath);
         var projectSnapshotManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
-        projectSnapshotManager.Setup(manager => manager.GetLoadedProject(ownerProject.Key))
+        projectSnapshotManager
+            .Setup(manager => manager.GetLoadedProject(ownerProject.Key))
             .Returns(ownerProject);
-        projectSnapshotManager.Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
-        projectSnapshotManager.Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
+        projectSnapshotManager
+            .Setup(manager => manager.TryGetLoadedProject(ownerProject.Key, out ownerProject))
+            .Returns(true);
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
             .Throws(new XunitException("Should not have been called."));
         var projectService = CreateProjectService(new TestSnapshotResolver(), projectSnapshotManager.Object);
 
@@ -314,12 +326,18 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     {
         // Arrange
         var projectFilePath = "C:/path/to/project.csproj";
-        var ownerProject = TestProjectSnapshot.Create(projectFilePath);
+        IProjectSnapshot ownerProject = TestProjectSnapshot.Create(projectFilePath);
         var projectSnapshotManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
-        projectSnapshotManager.Setup(manager => manager.GetLoadedProject(ownerProject.Key))
+        projectSnapshotManager
+            .Setup(manager => manager.GetLoadedProject(ownerProject.Key))
             .Returns(ownerProject);
-        projectSnapshotManager.Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
-        projectSnapshotManager.Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
+        projectSnapshotManager
+            .Setup(manager => manager.TryGetLoadedProject(ownerProject.Key, out ownerProject))
+            .Returns(true);
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
             .Callback<HostProject>((hostProject) =>
             {
                 Assert.Same(FallbackRazorConfiguration.Latest, hostProject.Configuration);
@@ -346,12 +364,18 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
     {
         // Arrange
         var projectFilePath = "C:/path/to/project.csproj";
-        var ownerProject = TestProjectSnapshot.Create(projectFilePath);
+        IProjectSnapshot ownerProject = TestProjectSnapshot.Create(projectFilePath);
         var projectSnapshotManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
-        projectSnapshotManager.Setup(manager => manager.GetLoadedProject(ownerProject.Key))
+        projectSnapshotManager
+            .Setup(manager => manager.GetLoadedProject(ownerProject.Key))
             .Returns(ownerProject);
-        projectSnapshotManager.Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
-        projectSnapshotManager.Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
+        projectSnapshotManager
+            .Setup(manager => manager.TryGetLoadedProject(ownerProject.Key, out ownerProject))
+            .Returns(true);
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectWorkspaceStateChanged(It.IsAny<ProjectKey>(), It.IsAny<ProjectWorkspaceState>()));
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
             .Callback<HostProject>((hostProject) =>
             {
                 Assert.Same(FallbackRazorConfiguration.MVC_1_1, hostProject.Configuration);
@@ -379,9 +403,15 @@ public class RazorProjectServiceTest(ITestOutputHelper testOutput) : LanguageSer
         // Arrange
         var projectSnapshotManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
         var projectKey = TestProjectKey.Create("C:/path/to/obj");
-        projectSnapshotManager.Setup(manager => manager.GetLoadedProject(projectKey))
+        projectSnapshotManager
+            .Setup(manager => manager.GetLoadedProject(projectKey))
             .Returns<IProjectSnapshot>(null);
-        projectSnapshotManager.Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
+        IProjectSnapshot projectResult = null;
+        projectSnapshotManager
+            .Setup(manager => manager.TryGetLoadedProject(projectKey, out projectResult))
+            .Returns(false);
+        projectSnapshotManager
+            .Setup(manager => manager.ProjectConfigurationChanged(It.IsAny<HostProject>()))
             .Throws(new XunitException("Should not have been called."));
         var projectService = CreateProjectService(new TestSnapshotResolver(), projectSnapshotManager.Object);
 

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/SnapshotResolverTest.cs

@@ -38,7 +38,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
         // Arrange
         var documentFilePath = @"C:\path\to\document.cshtml";
         var normalizedFilePath = "C:/path/to/document.cshtml";
-        var projectSnapshotManagerAccessor = new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher));
+        var projectSnapshotManagerAccessor = new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter));
         var snapshotResolver = new SnapshotResolver(projectSnapshotManagerAccessor, LoggerFactory);
         var miscProject = snapshotResolver.GetMiscellaneousProject();
 
@@ -62,7 +62,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = @"C:\path\to\document.cshtml";
-        var projectSnapshotManagerAccessor = new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher));
+        var projectSnapshotManagerAccessor = new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter));
         var snapshotResolver = new SnapshotResolver(projectSnapshotManagerAccessor, LoggerFactory);
 
         // Act
@@ -78,7 +78,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = "C:/path/to/document.cshtml";
-        var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher)), LoggerFactory);
+        var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter)), LoggerFactory);
 
         // Act
         var result = snapshotResolver.TryResolveAllProjects(documentFilePath, out var projects);
@@ -93,7 +93,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = "C:/path/to/document.cshtml";
-        var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher)), LoggerFactory);
+        var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter)), LoggerFactory);
         _ = snapshotResolver.GetMiscellaneousProject();
 
         // Act
@@ -124,7 +124,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = "C:/path/to/document.cshtml";
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
         snapshotManager.ProjectAdded(TestProjectSnapshot.Create("C:/other/path/to/project.csproj").HostProject);
 
@@ -141,7 +141,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = "C:/path/to/document.cshtml";
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var expectedProject = snapshotManager.CreateAndAddProject("C:/path/to/project.csproj");
         snapshotManager.CreateAndAddProject("C:/path/to/other/project.csproj");
         snapshotManager.CreateAndAddDocument(expectedProject, documentFilePath);
@@ -163,7 +163,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
         var documentFilePath = Path.Combine(TempDirectory.Instance.DirectoryPath, "file.cshtml");
         documentFilePath = FilePathNormalizer.Normalize(documentFilePath);
 
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
         var miscProject = (ProjectSnapshot)snapshotResolver.GetMiscellaneousProject();
         snapshotManager.CreateAndAddDocument(miscProject, documentFilePath);
@@ -182,7 +182,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         // Arrange
         var documentFilePath = "c:/path/to/document.cshtml";
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
 
         var ownerProject = snapshotManager.CreateAndAddProject("C:/Path/To/project.csproj");
@@ -200,7 +200,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     public void GetMiscellaneousProject_ProjectLoaded_ReturnsExistingProject()
     {
         // Arrange
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
 
         // Act
@@ -215,7 +215,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     public void GetMiscellaneousProject_ProjectNotLoaded_CreatesProjectAndReturnsCreatedProject()
     {
         // Arrange
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
 
         // Act
@@ -233,7 +233,7 @@ public class SnapshotResolverTest(ITestOutputHelper testOutput) : LanguageServer
     {
         filePath = FilePathNormalizer.Normalize(filePath);
 
-        snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         var snapshotResolver = new SnapshotResolver(new TestProjectSnapshotManagerAccessor(snapshotManager), LoggerFactory);
 
         if (addToMiscellaneous)

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/LanguageServer/TestProjectSnapshotManager.cs

@@ -3,32 +3,25 @@
 
 using Microsoft.AspNetCore.Razor.LanguageServer;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
-using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 
 namespace Microsoft.AspNetCore.Razor.Test.Common.LanguageServer;
 
 internal class TestProjectSnapshotManager : DefaultProjectSnapshotManager
 {
     private TestProjectSnapshotManager(
-        IErrorReporter errorReporter,
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider,
-        ProjectSnapshotManagerDispatcher dispatcher)
-        : base(errorReporter, triggers: [], workspace, projectEngineFactoryProvider, dispatcher)
+        ProjectSnapshotManagerDispatcher dispatcher,
+        IErrorReporter errorReporter)
+        : base(triggers: [], projectEngineFactoryProvider, dispatcher, errorReporter)
     {
     }
 
-    public static TestProjectSnapshotManager Create(IErrorReporter errorReporter, ProjectSnapshotManagerDispatcher dispatcher)
-    {
-        var services = TestServices.Create(workspaceServices: [], razorLanguageServices: []);
-        var workspace = TestWorkspace.Create(services);
-        var testProjectManager = new TestProjectSnapshotManager(errorReporter, workspace, ProjectEngineFactories.DefaultProvider, dispatcher);
-
-        return testProjectManager;
-    }
+    public static TestProjectSnapshotManager Create(ProjectSnapshotManagerDispatcher dispatcher, IErrorReporter errorReporter)
+        => new TestProjectSnapshotManager(ProjectEngineFactories.DefaultProvider, dispatcher, errorReporter);
 
     public bool AllowNotifyListeners { get; set; }
 
@@ -55,4 +48,9 @@ internal class TestProjectSnapshotManager : DefaultProjectSnapshotManager
             base.NotifyListeners(e);
         }
     }
+
+    private sealed class TestWorkspaceProvider(Workspace workspace) : IWorkspaceProvider
+    {
+        public Workspace GetWorkspace() => workspace;
+    }
 }

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/ProjectSystem/TestProjectSnapshotManager.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
-using System;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
 using Microsoft.CodeAnalysis;
@@ -12,15 +11,13 @@ using Moq;
 namespace Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
 
 internal class TestProjectSnapshotManager(
-    Workspace workspace,
     IProjectEngineFactoryProvider projectEngineFactoryProvider,
     ProjectSnapshotManagerDispatcher dispatcher)
     : DefaultProjectSnapshotManager(
-        Mock.Of<IErrorReporter>(MockBehavior.Strict),
-        Array.Empty<IProjectSnapshotChangeTrigger>(),
-        workspace,
+        triggers: [],
         projectEngineFactoryProvider,
-        dispatcher)
+        dispatcher,
+        Mock.Of<IErrorReporter>(MockBehavior.Strict))
 {
     public bool AllowNotifyListeners { get; set; }
 

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Tooling/Workspaces/WorkspaceTestBase.cs

@@ -8,22 +8,19 @@ using Microsoft.AspNetCore.Razor.ProjectEngineHost;
 using Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Xunit.Abstractions;
 
 namespace Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
 
-public abstract class WorkspaceTestBase : ToolingTestBase
+public abstract class WorkspaceTestBase(ITestOutputHelper testOutput) : ToolingTestBase(testOutput)
 {
     private bool _initialized;
     private HostServices? _hostServices;
     private Workspace? _workspace;
+    private IWorkspaceProvider? _workspaceProvider;
     private IProjectEngineFactoryProvider? _projectEngineFactoryProvider;
 
-    protected WorkspaceTestBase(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
-
     protected HostServices HostServices
     {
         get
@@ -42,6 +39,15 @@ public abstract class WorkspaceTestBase : ToolingTestBase
         }
     }
 
+    private protected IWorkspaceProvider WorkspaceProvider
+    {
+        get
+        {
+            EnsureInitialized();
+            return _workspaceProvider;
+        }
+    }
+
     private protected IProjectEngineFactoryProvider ProjectEngineFactoryProvider
     {
         get
@@ -67,13 +73,14 @@ public abstract class WorkspaceTestBase : ToolingTestBase
     {
     }
 
-    [MemberNotNull(nameof(_hostServices), nameof(_workspace), nameof(_projectEngineFactoryProvider))]
+    [MemberNotNull(nameof(_hostServices), nameof(_workspace), nameof(_workspaceProvider), nameof(_projectEngineFactoryProvider))]
     private void EnsureInitialized()
     {
         if (_initialized)
         {
             _hostServices.AssumeNotNull();
             _workspace.AssumeNotNull();
+            _workspaceProvider.AssumeNotNull();
             _projectEngineFactoryProvider.AssumeNotNull();
             return;
         }
@@ -92,6 +99,12 @@ public abstract class WorkspaceTestBase : ToolingTestBase
         _hostServices = TestServices.Create(workspaceServices, languageServices);
         _workspace = TestWorkspace.Create(_hostServices, ConfigureWorkspace);
         AddDisposable(_workspace);
+        _workspaceProvider = new TestWorkspaceProvider(_workspace);
         _initialized = true;
     }
+
+    private sealed class TestWorkspaceProvider(Workspace workspace) : IWorkspaceProvider
+    {
+        public Workspace GetWorkspace() => workspace;
+    }
 }

src/Razor/test/Microsoft.CodeAnalysis.Razor.Workspaces.Test/ProjectSystem/FallbackProjectManagerTest.cs

@@ -29,11 +29,11 @@ public class FallbackProjectManagerTest : WorkspaceTestBase
         _projectConfigurationFilePathStore = new TestProjectConfigurationFilePathStore();
 
         var dispatcher = Mock.Of<ProjectSnapshotManagerDispatcher>(MockBehavior.Strict);
-        _projectSnapshotManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, dispatcher);
+        _projectSnapshotManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, dispatcher);
 
         var projectSnapshotManagerAccessor = Mock.Of<IProjectSnapshotManagerAccessor>(a => a.Instance == _projectSnapshotManager, MockBehavior.Strict);
 
-        _fallbackProjectManger = new FallbackProjectManager(_projectConfigurationFilePathStore, languageServerFeatureOptions, projectSnapshotManagerAccessor, NoOpTelemetryReporter.Instance);
+        _fallbackProjectManger = new FallbackProjectManager(_projectConfigurationFilePathStore, languageServerFeatureOptions, projectSnapshotManagerAccessor, WorkspaceProvider, NoOpTelemetryReporter.Instance);
     }
 
     [Fact]

src/Razor/test/Microsoft.CodeAnalysis.Remote.Razor.Test/OutOfProcTagHelperResolverTest.TestProjectSnapshotManager.cs

@@ -1,10 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
-#nullable disable
-
 using System;
-using System.Linq;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
@@ -21,12 +18,11 @@ public partial class OutOfProcTagHelperResolverTest
         return dispatcher.Object;
     });
 
-    private class TestProjectSnapshotManager(Workspace workspace, IProjectEngineFactoryProvider projectEngineFactoryProvider) : DefaultProjectSnapshotManager(
-        Mock.Of<IErrorReporter>(MockBehavior.Strict),
-        Enumerable.Empty<IProjectSnapshotChangeTrigger>(),
-        workspace,
+    private class TestProjectSnapshotManager(IProjectEngineFactoryProvider projectEngineFactoryProvider) : DefaultProjectSnapshotManager(
+        triggers: [],
         projectEngineFactoryProvider,
-        s_projectSnapshotManagerDispatcher.Value)
+        s_projectSnapshotManagerDispatcher.Value,
+        Mock.Of<IErrorReporter>(MockBehavior.Strict))
     {
     }
 }

src/Razor/test/Microsoft.CodeAnalysis.Remote.Razor.Test/OutOfProcTagHelperResolverTest.TestResolver.cs

@@ -20,10 +20,10 @@ namespace Microsoft.CodeAnalysis.Remote.Razor;
 public partial class OutOfProcTagHelperResolverTest
 {
     private class TestResolver(
-        IProjectSnapshotManagerAccessor projectManagerAccessor,
+        IWorkspaceProvider workspaceProvider,
         IErrorReporter errorReporter,
         ITelemetryReporter telemetryReporter)
-        : OutOfProcTagHelperResolver(projectManagerAccessor, errorReporter, telemetryReporter)
+        : OutOfProcTagHelperResolver(workspaceProvider, errorReporter, telemetryReporter)
     {
         public Func<IProjectSnapshot, ValueTask<ImmutableArray<TagHelperDescriptor>>>? OnResolveOutOfProcess { get; init; }
 

src/Razor/test/Microsoft.CodeAnalysis.Remote.Razor.Test/OutOfProcTagHelperResolverTest.cs

@@ -27,6 +27,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
     private readonly HostProject _hostProject_For_NonSerializableConfiguration;
     private readonly Project _workspaceProject;
     private readonly IProjectSnapshotManagerAccessor _projectManagerAccessor;
+    private readonly IWorkspaceProvider _workspaceProvider;
 
     public OutOfProcTagHelperResolverTest(ITestOutputHelper testOutput)
         : base(testOutput)
@@ -45,6 +46,13 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
         var workspace = new AdhocWorkspace();
         AddDisposable(workspace);
 
+        var workspaceProviderMock = new Mock<IWorkspaceProvider>(MockBehavior.Strict);
+        workspaceProviderMock
+            .Setup(x => x.GetWorkspace())
+            .Returns(workspace);
+
+        _workspaceProvider = workspaceProviderMock.Object;
+
         var info = ProjectInfo.Create(ProjectId.CreateNewId("Test"), VersionStamp.Default, "Test", "Test", LanguageNames.CSharp, filePath: "Test.csproj");
         _workspaceProject = workspace.CurrentSolution.AddProject(info).GetProject(info.Id).AssumeNotNull();
 
@@ -55,7 +63,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
             CreateFactory("Test-2"));
 
         var projectEngineFactoryProvider = new ProjectEngineFactoryProvider(customFactories);
-        var projectManager = new TestProjectSnapshotManager(workspace, projectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(projectEngineFactoryProvider);
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock
@@ -80,11 +88,11 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
         // Arrange
         _projectManagerAccessor.Instance.ProjectAdded(_hostProject_For_2_0);
 
-        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key).AssumeNotNull();
+        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key);
 
         var calledOutOfProcess = false;
 
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance)
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance)
         {
             OnResolveOutOfProcess = (p) =>
             {
@@ -109,11 +117,11 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
         // Arrange
         _projectManagerAccessor.Instance.ProjectAdded(_hostProject_For_NonSerializableConfiguration);
 
-        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key).AssumeNotNull();
+        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key);
 
         var calledInProcess = false;
 
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance)
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance)
         {
             OnResolveInProcess = (p) =>
             {
@@ -138,13 +146,13 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
         // Arrange
         _projectManagerAccessor.Instance.ProjectAdded(_hostProject_For_2_0);
 
-        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key).AssumeNotNull();
+        var projectSnapshot = _projectManagerAccessor.Instance.GetLoadedProject(_hostProject_For_2_0.Key);
 
         var calledOutOfProcess = false;
         var calledInProcess = false;
 
         var cancellationToken = new CancellationToken(canceled: true);
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance)
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance)
         {
             OnResolveInProcess = (p) =>
             {
@@ -172,7 +180,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
     public void CalculateTagHelpersFromDelta_NewProject()
     {
         // Arrange
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance);
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance);
         var initialDelta = new TagHelperDeltaResult(IsDelta: false, ResultId: 1, Project1TagHelperChecksums, ImmutableArray<Checksum>.Empty);
 
         // Act
@@ -186,7 +194,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
     public void CalculateTagHelpersFromDelta_DeltaFailedToApplyToKnownProject()
     {
         // Arrange
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance);
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance);
         var initialDelta = new TagHelperDeltaResult(IsDelta: false, ResultId: 1, Project1TagHelperChecksums, ImmutableArray<Checksum>.Empty);
         resolver.PublicProduceChecksumsFromDelta(Project1Id, lastResultId: -1, initialDelta);
         var newTagHelperSet = ImmutableArray.Create(TagHelper1_Project1.Checksum);
@@ -203,7 +211,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
     public void CalculateTagHelpersFromDelta_NoopResult()
     {
         // Arrange
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance);
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance);
         var initialDelta = new TagHelperDeltaResult(IsDelta: false, ResultId: 1, Project1TagHelperChecksums, ImmutableArray<Checksum>.Empty);
         resolver.PublicProduceChecksumsFromDelta(Project1Id, lastResultId: -1, initialDelta);
         var noopDelta = new TagHelperDeltaResult(IsDelta: true, initialDelta.ResultId, ImmutableArray<Checksum>.Empty, ImmutableArray<Checksum>.Empty);
@@ -219,7 +227,7 @@ public partial class OutOfProcTagHelperResolverTest : TagHelperDescriptorTestBas
     public void CalculateTagHelpersFromDelta_ReplacedTagHelpers()
     {
         // Arrange
-        var resolver = new TestResolver(_projectManagerAccessor, ErrorReporter, NoOpTelemetryReporter.Instance);
+        var resolver = new TestResolver(_workspaceProvider, ErrorReporter, NoOpTelemetryReporter.Instance);
         var initialDelta = new TagHelperDeltaResult(IsDelta: false, ResultId: 1, Project1TagHelperChecksums, ImmutableArray<Checksum>.Empty);
         resolver.PublicProduceChecksumsFromDelta(Project1Id, lastResultId: -1, initialDelta);
         var changedDelta = new TagHelperDeltaResult(IsDelta: true, initialDelta.ResultId + 1, ImmutableArray.Create(TagHelper2_Project2.Checksum), ImmutableArray.Create(TagHelper2_Project1.Checksum));

src/Razor/test/Microsoft.VisualStudio.Editor.Razor.Test/DefaultRazorDocumentManagerTest.cs

@@ -44,11 +44,23 @@ public class DefaultRazorDocumentManagerTest : ProjectSnapshotManagerDispatcherT
             c => c.IsOfType(It.IsAny<string>()) == false,
             MockBehavior.Strict);
 
-        var projectManager = Mock.Of<ProjectSnapshotManagerBase>(
-            p => p.GetProjects() == ImmutableArray<IProjectSnapshot>.Empty &&
-                 p.GetLoadedProject(It.IsAny<ProjectKey>()) == null &&
-                 p.GetAllProjectKeys(It.IsAny<string>()) == ImmutableArray<ProjectKey>.Empty,
-            MockBehavior.Strict);
+        var projectManagerMock = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
+        projectManagerMock
+            .Setup(p => p.GetAllProjectKeys(It.IsAny<string>()))
+            .Returns(ImmutableArray<ProjectKey>.Empty);
+        projectManagerMock
+            .Setup(p => p.GetProjects())
+            .Returns(ImmutableArray<IProjectSnapshot>.Empty);
+
+        IProjectSnapshot projectResult = null;
+        projectManagerMock
+            .Setup(p => p.GetLoadedProject(It.IsAny<ProjectKey>()))
+            .Returns(projectResult);
+        projectManagerMock
+            .Setup(p => p.TryGetLoadedProject(It.IsAny<ProjectKey>(), out projectResult))
+            .Returns(false);
+
+        var projectManager = projectManagerMock.Object;
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock
@@ -64,7 +76,6 @@ public class DefaultRazorDocumentManagerTest : ProjectSnapshotManagerDispatcherT
         importDocumentManager.Setup(m => m.OnSubscribed(It.IsAny<VisualStudioDocumentTracker>())).Verifiable();
         importDocumentManager.Setup(m => m.OnUnsubscribed(It.IsAny<VisualStudioDocumentTracker>())).Verifiable();
         _importDocumentManager = importDocumentManager.Object;
-
     }
 
     [UIFact]

src/Razor/test/Microsoft.VisualStudio.Editor.Razor.Test/DefaultVisualStudioDocumentTrackerTest.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.Editor;
 using Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
@@ -54,7 +53,7 @@ public class DefaultVisualStudioDocumentTrackerTest : ProjectSnapshotManagerDisp
 
         _workspaceEditorSettings = new DefaultWorkspaceEditorSettings(Mock.Of<IClientSettingsManager>(MockBehavior.Strict));
 
-        _projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher) { AllowNotifyListeners = true };
+        _projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher) { AllowNotifyListeners = true };
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock
@@ -166,7 +165,7 @@ public class DefaultVisualStudioDocumentTrackerTest : ProjectSnapshotManagerDisp
         // Arrange
         _projectManager.ProjectAdded(_hostProject);
 
-        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_hostProject.Key)!, ProjectChangeKind.ProjectAdded);
+        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_hostProject.Key), ProjectChangeKind.ProjectAdded);
 
         var called = false;
         _documentTracker.ContextChanged += (sender, args) =>
@@ -189,7 +188,7 @@ public class DefaultVisualStudioDocumentTrackerTest : ProjectSnapshotManagerDisp
         // Arrange
         _projectManager.ProjectAdded(_hostProject);
 
-        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_hostProject.Key)!, ProjectChangeKind.ProjectChanged);
+        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_hostProject.Key), ProjectChangeKind.ProjectChanged);
 
         var called = false;
         _documentTracker.ContextChanged += (sender, args) =>
@@ -239,7 +238,7 @@ public class DefaultVisualStudioDocumentTrackerTest : ProjectSnapshotManagerDisp
         // Arrange
         _projectManager.ProjectAdded(_otherHostProject);
 
-        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_otherHostProject.Key)!, ProjectChangeKind.ProjectChanged);
+        var e = new ProjectChangeEventArgs(null!, _projectManager.GetLoadedProject(_otherHostProject.Key), ProjectChangeKind.ProjectChanged);
 
         var called = false;
         _documentTracker.ContextChanged += (sender, args) => called = true;

src/Razor/test/Microsoft.VisualStudio.Editor.Razor.Test/Documents/EditorDocumentManagerListenerTest.cs

@@ -9,6 +9,7 @@ using Microsoft.AspNetCore.Razor.Test.Common.ProjectSystem;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.Threading;
 using Moq;
@@ -56,8 +57,10 @@ public class EditorDocumentManagerListenerTest : ProjectSnapshotManagerDispatche
             .Setup(e => e.RemoveDocument(It.IsAny<EditorDocument>()))
             .Callback<EditorDocument>(doc => Assert.Same(document, doc));
 
+        var workspaceProvider = Mock.Of<IWorkspaceProvider>(MockBehavior.Strict);
+
         var listener = new EditorDocumentManagerListener(
-            Dispatcher, JoinableTaskFactory.Context, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
+            workspaceProvider, Dispatcher, JoinableTaskContext, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
 
         var projectFilePath = "/Path/to/project.csproj";
         var project = Mock.Of<IProjectSnapshot>(p => p.Key == TestProjectKey.Create("/Path/to/obj") && p.FilePath == projectFilePath, MockBehavior.Strict);
@@ -84,8 +87,10 @@ public class EditorDocumentManagerListenerTest : ProjectSnapshotManagerDispatche
             .Setup(e => e.RemoveDocument(It.IsAny<EditorDocument>()))
             .Callback<EditorDocument>(doc => Assert.Same(document, doc));
 
+        var workspaceProvider = Mock.Of<IWorkspaceProvider>(MockBehavior.Strict);
+
         var listener = new EditorDocumentManagerListener(
-            Dispatcher, JoinableTaskFactory.Context, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
+            workspaceProvider, Dispatcher, JoinableTaskContext, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
 
         var projectFilePath = "/Path/to/project.csproj";
         var project = Mock.Of<IProjectSnapshot>(p =>
@@ -118,8 +123,10 @@ public class EditorDocumentManagerListenerTest : ProjectSnapshotManagerDispatche
                 Assert.Same(closed, onClosed);
             });
 
+        var workspaceProvider = Mock.Of<IWorkspaceProvider>(MockBehavior.Strict);
+
         var listener = new EditorDocumentManagerListener(
-            Dispatcher, JoinableTaskFactory.Context, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
+            workspaceProvider, Dispatcher, JoinableTaskContext, editorDocumentManger.Object, changedOnDisk, changedInEditor, opened, closed);
 
         var projectFilePath = "/Path/to/project.csproj";
         var project = Mock.Of<IProjectSnapshot>(p => p.Key == TestProjectKey.Create("/Path/to/obj") && p.FilePath == projectFilePath, MockBehavior.Strict);
@@ -140,8 +147,10 @@ public class EditorDocumentManagerListenerTest : ProjectSnapshotManagerDispatche
             .Setup(e => e.GetOrCreateDocument(It.IsAny<DocumentKey>(), It.IsAny<string>(), It.IsAny<ProjectKey>(), It.IsAny<EventHandler>(), It.IsAny<EventHandler>(), It.IsAny<EventHandler>(), It.IsAny<EventHandler>()))
             .Returns(GetEditorDocument(isOpen: true));
 
+        var workspaceProvider = Mock.Of<IWorkspaceProvider>(MockBehavior.Strict);
+
         var listener = new EditorDocumentManagerListener(
-            Dispatcher, JoinableTaskFactory.Context, editorDocumentManger.Object, onChangedOnDisk: null, onChangedInEditor: null, onOpened: opened, onClosed: null);
+            workspaceProvider, Dispatcher, JoinableTaskContext, editorDocumentManger.Object, onChangedOnDisk: null, onChangedInEditor: null, onOpened: opened, onClosed: null);
 
         var projectFilePath = "/Path/to/project.csproj";
         var project = Mock.Of<IProjectSnapshot>(p => p.Key == TestProjectKey.Create("/Path/to/obj") && p.FilePath == projectFilePath, MockBehavior.Strict);
@@ -158,7 +167,7 @@ public class EditorDocumentManagerListenerTest : ProjectSnapshotManagerDispatche
         var document = new EditorDocument(
             documentManager ?? Mock.Of<EditorDocumentManager>(MockBehavior.Strict),
             Dispatcher,
-            JoinableTaskFactory.Context,
+            JoinableTaskContext,
             _projectFilePath,
             _documentFilePath,
             _projectKey,

src/Razor/test/Microsoft.VisualStudio.Editor.Razor.Test/ProjectWorkspaceStateGeneratorTest.cs

@@ -26,7 +26,6 @@ public class ProjectWorkspaceStateGeneratorTest : ProjectSnapshotManagerDispatch
 {
     private readonly IProjectEngineFactoryProvider _projectEngineFactoryProvider;
     private readonly TestTagHelperResolver _tagHelperResolver;
-    private readonly Workspace _workspace;
     private readonly Project _workspaceProject;
     private readonly ProjectSnapshot _projectSnapshot;
     private readonly ProjectWorkspaceState _projectWorkspaceStateWithTagHelpers;
@@ -40,10 +39,11 @@ public class ProjectWorkspaceStateGeneratorTest : ProjectSnapshotManagerDispatch
             ImmutableArray.Create(TagHelperDescriptorBuilder.Create("ResolvableTagHelper", "TestAssembly").Build()));
 
         var testServices = TestServices.Create([], []);
-        _workspace = TestWorkspace.Create(testServices);
-        AddDisposable(_workspace);
+        var workspace = TestWorkspace.Create(testServices);
+        AddDisposable(workspace);
+
         var projectId = ProjectId.CreateNewId("Test");
-        var solution = _workspace.CurrentSolution.AddProject(ProjectInfo.Create(
+        var solution = workspace.CurrentSolution.AddProject(ProjectInfo.Create(
             projectId,
             VersionStamp.Default,
             "Test",
@@ -59,7 +59,7 @@ public class ProjectWorkspaceStateGeneratorTest : ProjectSnapshotManagerDispatch
 
     private IProjectSnapshotManagerAccessor CreateProjectManagerAccessor()
     {
-        var projectManager = new TestProjectSnapshotManager(_workspace, _projectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(_projectEngineFactoryProvider, Dispatcher);
         var mock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         mock.SetupGet(x => x.Instance).Returns(projectManager);
 

src/Razor/test/Microsoft.VisualStudio.LanguageServerClient.Razor.Test/CSharpVirtualDocumentFactoryTest.cs

@@ -86,7 +86,7 @@ public class CSharpVirtualDocumentFactoryTest : ToolingTestBase
         var uriProvider = Mock.Of<FileUriProvider>(provider => provider.GetOrCreate(_razorLSPBuffer) == uri, MockBehavior.Strict);
         Mock.Get(uriProvider).Setup(p => p.AddOrUpdate(It.IsAny<ITextBuffer>(), It.IsAny<Uri>())).Verifiable();
 
-        var projectSnapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, new TestDispatcher());
+        var projectSnapshotManager = TestProjectSnapshotManager.Create(new TestDispatcher(), ErrorReporter);
         var project = projectSnapshotManager.CreateAndAddProject(@"C:\path\to\project.csproj");
         projectSnapshotManager.CreateAndAddDocument(project, @"C:\path\to\file.razor");
         var projectSnapshotManagerAccessor = Mock.Of<IProjectSnapshotManagerAccessor>(a => a.Instance == projectSnapshotManager, MockBehavior.Strict);
@@ -110,7 +110,7 @@ public class CSharpVirtualDocumentFactoryTest : ToolingTestBase
         var uriProvider = Mock.Of<FileUriProvider>(provider => provider.GetOrCreate(_razorLSPBuffer) == uri, MockBehavior.Strict);
         Mock.Get(uriProvider).Setup(p => p.AddOrUpdate(It.IsAny<ITextBuffer>(), It.IsAny<Uri>())).Verifiable();
 
-        var projectSnapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, new TestDispatcher());
+        var projectSnapshotManager = TestProjectSnapshotManager.Create(new TestDispatcher(), ErrorReporter);
         var project = TestProjectSnapshot.Create(@"C:\path\to\project1.csproj", @"C:\path\to\obj1", Array.Empty<string>(), RazorConfiguration.Default, projectWorkspaceState: null);
         projectSnapshotManager.ProjectAdded(project.HostProject);
         projectSnapshotManager.CreateAndAddDocument(project, @"C:\path\to\file.razor");

src/Razor/test/Microsoft.VisualStudio.LanguageServerClient.Razor.Test/RazorProjectInfoPublisherTest.cs

@@ -645,7 +645,7 @@ public class RazorProjectInfoPublisherTest(ITestOutputHelper testOutput) : Langu
 
     internal ProjectSnapshotManagerBase CreateProjectSnapshotManager(bool allowNotifyListeners = false)
     {
-        var snapshotManager = TestProjectSnapshotManager.Create(ErrorReporter, Dispatcher);
+        var snapshotManager = TestProjectSnapshotManager.Create(Dispatcher, ErrorReporter);
         snapshotManager.AllowNotifyListeners = allowNotifyListeners;
 
         return snapshotManager;

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/DocumentGenerator/BackgroundDocumentGeneratorTest.cs

@@ -53,7 +53,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task ProcessDocument_LongDocumentParse_DoesNotUpdateAfterSuppress()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
         projectManager.ProjectAdded(_hostProject1);
 
         // We utilize a task completion source here so we can "fake" a document parse taking a significant amount of time
@@ -99,7 +99,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task ProcessDocument_SwallowsIOExceptions()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
         projectManager.ProjectAdded(_hostProject1);
 
         var textLoader = new Mock<TextLoader>(MockBehavior.Strict);
@@ -130,7 +130,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task ProcessDocument_SwallowsUnauthorizedAccessExceptions()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
         projectManager.ProjectAdded(_hostProject1);
 
         var textLoader = new Mock<TextLoader>(MockBehavior.Strict);
@@ -161,7 +161,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task Queue_ProcessesNotifications_AndGoesBackToSleep()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
         projectManager.ProjectAdded(_hostProject1);
         projectManager.ProjectAdded(_hostProject2);
         projectManager.DocumentAdded(_hostProject1.Key, _documents[0], null);
@@ -200,7 +200,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task Queue_ProcessesNotifications_AndRestarts()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
         projectManager.ProjectAdded(_hostProject1);
         projectManager.ProjectAdded(_hostProject2);
         projectManager.DocumentAdded(_hostProject1.Key, _documents[0], null);
@@ -263,7 +263,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task DocumentChanged_ReparsesRelatedFiles()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher)
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher)
         {
             AllowNotifyListeners = true,
         };
@@ -326,7 +326,7 @@ public class BackgroundDocumentGeneratorTest : ProjectSnapshotManagerDispatcherW
     public async Task DocumentRemoved_ReparsesRelatedFiles()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher)
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher)
         {
             AllowNotifyListeners = true,
         };

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/ProjectSystem/DefaultProjectSnapshotManagerTest.cs

@@ -51,7 +51,7 @@ public class DefaultProjectSnapshotManagerTest : ProjectSnapshotManagerDispatche
         _hostProject2 = new HostProject(TestProjectData.AnotherProject.FilePath, TestProjectData.AnotherProject.IntermediateOutputPath, FallbackRazorConfiguration.MVC_2_1, TestProjectData.AnotherProject.RootNamespace);
         _hostProjectWithConfigurationChange = new HostProject(TestProjectData.SomeProject.FilePath, TestProjectData.SomeProject.IntermediateOutputPath, FallbackRazorConfiguration.MVC_1_0, TestProjectData.SomeProject.RootNamespace);
 
-        _projectManager = new TestProjectSnapshotManager(triggers: [], Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        _projectManager = new TestProjectSnapshotManager(triggers: [], ProjectEngineFactoryProvider, Dispatcher);
 
         _projectWorkspaceStateWithTagHelpers = ProjectWorkspaceState.Create(someTagHelpers);
 
@@ -70,7 +70,7 @@ public class DefaultProjectSnapshotManagerTest : ProjectSnapshotManagerDispatche
         var triggers = new[] { defaultPriorityTrigger, highPriorityTrigger };
 
         // Act
-        var projectManager = new TestProjectSnapshotManager(triggers, Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        var projectManager = new TestProjectSnapshotManager(triggers, ProjectEngineFactoryProvider, Dispatcher);
 
         // Assert
         Assert.Equal(new[] { "highPriority", "lowPriority" }, initializedOrder);
@@ -649,10 +649,9 @@ public class DefaultProjectSnapshotManagerTest : ProjectSnapshotManagerDispatche
 
     private class TestProjectSnapshotManager(
         IEnumerable<IProjectSnapshotChangeTrigger> triggers,
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider,
         ProjectSnapshotManagerDispatcher dispatcher)
-        : DefaultProjectSnapshotManager(Mock.Of<IErrorReporter>(MockBehavior.Strict), triggers, workspace, projectEngineFactoryProvider, dispatcher)
+        : DefaultProjectSnapshotManager(triggers, projectEngineFactoryProvider, dispatcher, Mock.Of<IErrorReporter>(MockBehavior.Strict))
     {
         public ProjectChangeKind? ListenersNotifiedOf { get; private set; }
 

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/ProjectSystem/DefaultRazorDynamicFileInfoProviderTest.cs

@@ -40,7 +40,7 @@ public class DefaultRazorDynamicFileInfoProviderTest : WorkspaceTestBase
     {
         _documentServiceFactory = new DefaultRazorDocumentServiceProviderFactory();
         _editorFeatureDetector = Mock.Of<LSPEditorFeatureDetector>(MockBehavior.Strict);
-        _projectSnapshotManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, new TestProjectSnapshotManagerDispatcher())
+        _projectSnapshotManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, new TestProjectSnapshotManagerDispatcher())
         {
             AllowNotifyListeners = true
         };
@@ -59,9 +59,9 @@ public class DefaultRazorDynamicFileInfoProviderTest : WorkspaceTestBase
         var projectSnapshotManagerAccessor = Mock.Of<IProjectSnapshotManagerAccessor>(a => a.Instance == _projectSnapshotManager, MockBehavior.Strict);
 
         var projectConfigurationFilePathStore = Mock.Of<ProjectConfigurationFilePathStore>(MockBehavior.Strict);
-        var fallbackProjectManager = new FallbackProjectManager(projectConfigurationFilePathStore, languageServerFeatureOptions, projectSnapshotManagerAccessor, NoOpTelemetryReporter.Instance);
+        var fallbackProjectManager = new FallbackProjectManager(projectConfigurationFilePathStore, languageServerFeatureOptions, projectSnapshotManagerAccessor, WorkspaceProvider, NoOpTelemetryReporter.Instance);
 
-        _provider = new DefaultRazorDynamicFileInfoProvider(_documentServiceFactory, _editorFeatureDetector, filePathService, projectSnapshotManagerAccessor, fallbackProjectManager);
+        _provider = new DefaultRazorDynamicFileInfoProvider(_documentServiceFactory, _editorFeatureDetector, filePathService, WorkspaceProvider, fallbackProjectManager);
         _testAccessor = _provider.GetTestAccessor();
         _provider.Initialize(_projectSnapshotManager);
 

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/ProjectSystem/DefaultWindowsRazorProjectHostTest.cs

@@ -37,7 +37,7 @@ public class DefaultWindowsRazorProjectHostTest : ProjectSnapshotManagerDispatch
     public DefaultWindowsRazorProjectHostTest(ITestOutputHelper testOutput)
         : base(testOutput)
     {
-        _projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        _projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock
@@ -1247,15 +1247,13 @@ public class DefaultWindowsRazorProjectHostTest : ProjectSnapshotManagerDispatch
     }
 
     private class TestProjectSnapshotManager(
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider,
         ProjectSnapshotManagerDispatcher dispatcher)
         : DefaultProjectSnapshotManager(
-            Mock.Of<IErrorReporter>(MockBehavior.Strict),
             triggers: [],
-            workspace,
             projectEngineFactoryProvider,
-            dispatcher)
+            dispatcher,
+            Mock.Of<IErrorReporter>(MockBehavior.Strict))
     {
     }
 }

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/ProjectSystem/FallbackWindowsRazorProjectHostTest.cs

@@ -35,7 +35,7 @@ public class FallbackWindowsRazorProjectHostTest : ProjectSnapshotManagerDispatc
     public FallbackWindowsRazorProjectHostTest(ITestOutputHelper testOutput)
         : base(testOutput)
     {
-        _projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, Dispatcher);
+        _projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, Dispatcher);
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock
@@ -674,14 +674,12 @@ public class FallbackWindowsRazorProjectHostTest : ProjectSnapshotManagerDispatc
     }
 
     private class TestProjectSnapshotManager(
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider,
         ProjectSnapshotManagerDispatcher dispatcher) : DefaultProjectSnapshotManager(
-              Mock.Of<IErrorReporter>(MockBehavior.Strict),
-              triggers: [],
-              workspace,
-              projectEngineFactoryProvider,
-              dispatcher)
+            triggers: [],
+            projectEngineFactoryProvider,
+            dispatcher,
+            Mock.Of<IErrorReporter>(MockBehavior.Strict))
     {
     }
 }

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/ProjectSystem/WorkspaceProjectStateChangeDetectorTest.cs

@@ -140,12 +140,12 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
         _workQueueTestAccessor.NotifyBackgroundWorkStarting = new ManualResetEventSlim(initialState: false);
 
         Workspace.TryApplyChanges(_solutionWithTwoProjects);
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
         workspaceStateGenerator.ClearQueue();
         _workQueueTestAccessor.NotifyBackgroundWorkStarting.Wait();
@@ -178,13 +178,13 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
 
         await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
@@ -228,13 +228,13 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
 
         await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
@@ -280,11 +280,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
             projectManager.ProjectAdded(_hostProjectOne);
@@ -315,12 +315,12 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
 
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
 
         await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
@@ -360,10 +360,10 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
 
         var solution = _solutionWithTwoProjects.WithProjectAssemblyName(_projectNumberOne.Id, "Changed");
@@ -390,11 +390,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
         Workspace.TryApplyChanges(_solutionWithTwoProjects);
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
         workspaceStateGenerator.ClearQueue();
 
@@ -422,11 +422,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
         Workspace.TryApplyChanges(_solutionWithTwoProjects);
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
         workspaceStateGenerator.ClearQueue();
 
@@ -454,11 +454,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
         Workspace.TryApplyChanges(_solutionWithTwoProjects);
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
         workspaceStateGenerator.ClearQueue();
 
@@ -486,11 +486,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue);
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue);
         _workQueueTestAccessor.BlockBackgroundWorkStart = new ManualResetEventSlim(initialState: false);
 
         Workspace.TryApplyChanges(_solutionWithTwoProjects);
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectOne), DisposalToken);
         workspaceStateGenerator.ClearQueue();
 
@@ -535,11 +535,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
             projectManager.ProjectAdded(_hostProjectOne);
@@ -564,11 +564,11 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
     {
         // Arrange
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
-        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, s_dispatcher, TestLanguageServerFeatureOptions.Instance, _workQueue)
+        var detector = new WorkspaceProjectStateChangeDetector(workspaceStateGenerator, TestLanguageServerFeatureOptions.Instance, WorkspaceProvider, ErrorReporter, s_dispatcher, _workQueue)
         {
             NotifyWorkspaceChangedEventComplete = new ManualResetEventSlim(initialState: false),
         };
-        var projectManager = new TestProjectSnapshotManager(new[] { detector }, Workspace, ProjectEngineFactoryProvider);
+        var projectManager = new TestProjectSnapshotManager(new[] { detector }, ProjectEngineFactoryProvider);
         await s_dispatcher.RunOnDispatcherThreadAsync(() => projectManager.ProjectAdded(_hostProjectThree), DisposalToken);
 
         var solution = _solutionWithOneProject;
@@ -776,14 +776,12 @@ public class WorkspaceProjectStateChangeDetectorTest : WorkspaceTestBase
 
     private class TestProjectSnapshotManager(
         IEnumerable<IProjectSnapshotChangeTrigger> triggers,
-        Workspace workspace,
         IProjectEngineFactoryProvider projectEngineFactoryProvider)
         : DefaultProjectSnapshotManager(
-            Mock.Of<IErrorReporter>(MockBehavior.Strict),
             triggers,
-            workspace,
             projectEngineFactoryProvider,
-            s_dispatcher)
+            s_dispatcher,
+            Mock.Of<IErrorReporter>(MockBehavior.Strict))
     {
     }
 

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/VsSolutionUpdatesProjectSnapshotChangeTriggerTest.cs

@@ -16,6 +16,7 @@ using Microsoft.AspNetCore.Razor.Test.Common.Workspaces;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
 using Microsoft.VisualStudio.Editor.Razor;
 using Microsoft.VisualStudio.LanguageServices.Razor.Test;
 using Microsoft.VisualStudio.Shell.Interop;
@@ -34,6 +35,7 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
     private readonly HostProject _someOtherProject;
     private Project _someWorkspaceProject;
     private readonly CodeAnalysis.Workspace _workspace;
+    private readonly IWorkspaceProvider _workspaceProvider;
 
     public VsSolutionUpdatesProjectSnapshotChangeTriggerTest(ITestOutputHelper testOutput)
         : base(testOutput)
@@ -59,6 +61,13 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
                             .WithAssemblyPath(Path.Combine(_someProject.IntermediateOutputPath, "SomeProject.dll"))));
             });
         AddDisposable(_workspace);
+
+        var workspaceProviderMock = new Mock<IWorkspaceProvider>(MockBehavior.Strict);
+        workspaceProviderMock
+            .Setup(x => x.GetWorkspace())
+            .Returns(_workspace);
+
+        _workspaceProvider = workspaceProviderMock.Object;
     }
 
     [Fact]
@@ -79,8 +88,9 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
             services.Object,
             Mock.Of<TextBufferProjectService>(MockBehavior.Strict),
             Mock.Of<IProjectWorkspaceStateGenerator>(MockBehavior.Strict),
+            _workspaceProvider,
             s_dispatcher,
-            JoinableTaskFactory.Context);
+            JoinableTaskContext);
 
         // Act
         trigger.Initialize(Mock.Of<ProjectSnapshotManagerBase>(MockBehavior.Strict));
@@ -99,21 +109,23 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
             .Setup(b => b.AdviseUpdateSolutionEvents(It.IsAny<VsSolutionUpdatesProjectSnapshotChangeTrigger>(), out cookie))
             .Returns(VSConstants.S_OK);
 
-        var context = JoinableTaskFactory.Context;
-
         var services = new Mock<IServiceProvider>(MockBehavior.Strict);
-        services.Setup(s => s.GetService(It.Is<Type>(f => f == typeof(SVsSolutionBuildManager)))).Callback(() => Assert.True(context.IsOnMainThread)).Returns(buildManager.Object);
+        services
+            .Setup(s => s.GetService(It.Is<Type>(f => f == typeof(SVsSolutionBuildManager))))
+            .Callback(() => Assert.True(JoinableTaskContext.IsOnMainThread))
+            .Returns(buildManager.Object);
 
         var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(
             services.Object,
             Mock.Of<TextBufferProjectService>(MockBehavior.Strict),
             Mock.Of<IProjectWorkspaceStateGenerator>(MockBehavior.Strict),
+            _workspaceProvider,
             s_dispatcher,
-            context);
+            JoinableTaskContext);
 
         await Task.Run(() =>
         {
-            Assert.False(context.IsOnMainThread);
+            Assert.False(JoinableTaskContext.IsOnMainThread);
             trigger.Initialize(Mock.Of<ProjectSnapshotManagerBase>(MockBehavior.Strict));
             return Task.CompletedTask;
         });
@@ -123,7 +135,7 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
     public async Task SolutionClosing_CancelsActiveWork()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(_workspace, ProjectEngineFactories.DefaultProvider, s_dispatcher)
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactories.DefaultProvider, s_dispatcher)
         {
             AllowNotifyListeners = true,
         };
@@ -140,7 +152,13 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
         projectService.Setup(p => p.GetProjectPath(It.IsAny<IVsHierarchy>())).Returns(expectedProjectPath);
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
 
-        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(TestServiceProvider.Instance, projectService.Object, workspaceStateGenerator, s_dispatcher, JoinableTaskFactory.Context);
+        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(
+            TestServiceProvider.Instance,
+            projectService.Object,
+            workspaceStateGenerator,
+            _workspaceProvider,
+            s_dispatcher,
+            JoinableTaskContext);
         trigger.Initialize(projectManager);
         trigger.UpdateProjectCfg_Done(Mock.Of<IVsHierarchy>(MockBehavior.Strict), pCfgProj: default, pCfgSln: default, dwAction: default, fSuccess: default, fCancel: default);
         await trigger.CurrentUpdateTaskForTests;
@@ -163,7 +181,7 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
     public async Task OnProjectBuiltAsync_KnownProject_EnqueuesProjectStateUpdate()
     {
         // Arrange
-        var projectManager = new TestProjectSnapshotManager(_workspace, ProjectEngineFactories.DefaultProvider, s_dispatcher);
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactories.DefaultProvider, s_dispatcher);
         var expectedProjectPath = _someProject.FilePath;
         var expectedProjectSnapshot = await s_dispatcher.RunOnDispatcherThreadAsync(() =>
         {
@@ -177,7 +195,13 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
         projectService.Setup(p => p.GetProjectPath(It.IsAny<IVsHierarchy>())).Returns(expectedProjectPath);
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
 
-        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(TestServiceProvider.Instance, projectService.Object, workspaceStateGenerator, s_dispatcher, JoinableTaskFactory.Context);
+        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(
+            TestServiceProvider.Instance,
+            projectService.Object,
+            workspaceStateGenerator,
+            _workspaceProvider,
+            s_dispatcher,
+            JoinableTaskContext);
         trigger.Initialize(projectManager);
 
         // Act
@@ -206,7 +230,7 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
 
         var projectEngineFactoryProvider = Mock.Of<IProjectEngineFactoryProvider>(MockBehavior.Strict);
 
-        var projectSnapshot = new ProjectSnapshot(
+        IProjectSnapshot projectSnapshot = new ProjectSnapshot(
             ProjectState.Create(
                 projectEngineFactoryProvider,
                 new HostProject("/Some/Unknown/Path.csproj", "/Some/Unknown/obj", RazorConfiguration.Default, "Path"),
@@ -217,16 +241,24 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
         projectService.Setup(p => p.GetProjectPath(It.IsAny<IVsHierarchy>())).Returns(expectedProjectPath);
 
         var projectManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
-        projectManager.SetupGet(p => p.Workspace).Returns(_workspace);
         projectManager
             .Setup(p => p.GetAllProjectKeys(projectSnapshot.FilePath))
             .Returns(ImmutableArray.Create(projectSnapshot.Key));
         projectManager
             .Setup(p => p.GetLoadedProject(projectSnapshot.Key))
             .Returns(projectSnapshot);
+        projectManager
+            .Setup(p => p.TryGetLoadedProject(projectSnapshot.Key, out projectSnapshot))
+            .Returns(true);
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
 
-        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(services.Object, projectService.Object, workspaceStateGenerator, s_dispatcher, JoinableTaskFactory.Context);
+        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(
+            services.Object,
+            projectService.Object,
+            workspaceStateGenerator,
+            _workspaceProvider,
+            s_dispatcher,
+            JoinableTaskContext);
         trigger.Initialize(projectManager.Object);
 
         // Act
@@ -255,13 +287,18 @@ public class VsSolutionUpdatesProjectSnapshotChangeTriggerTest : ToolingTestBase
         projectService.Setup(p => p.GetProjectPath(It.IsAny<IVsHierarchy>())).Returns(expectedProjectPath);
 
         var projectManager = new Mock<ProjectSnapshotManagerBase>(MockBehavior.Strict);
-        projectManager.SetupGet(p => p.Workspace).Returns(_workspace);
         projectManager
             .Setup(p => p.GetAllProjectKeys(expectedProjectPath))
             .Returns(ImmutableArray<ProjectKey>.Empty);
         var workspaceStateGenerator = new TestProjectWorkspaceStateGenerator();
 
-        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(services.Object, projectService.Object, workspaceStateGenerator, s_dispatcher, JoinableTaskFactory.Context);
+        var trigger = new VsSolutionUpdatesProjectSnapshotChangeTrigger(
+            services.Object,
+            projectService.Object,
+            workspaceStateGenerator,
+            _workspaceProvider,
+            s_dispatcher,
+            JoinableTaskContext);
         trigger.Initialize(projectManager.Object);
 
         // Act

src/Razor/test/Microsoft.VisualStudio.LiveShare.Razor.Test/Guest/ProjectSnapshotSynchronizationServiceTest.cs

@@ -30,7 +30,7 @@ public class ProjectSnapshotSynchronizationServiceTest : ProjectSnapshotManagerD
     {
         _sessionContext = new TestCollaborationSession(isHost: false);
 
-        var projectManager = new TestProjectSnapshotManager(Workspace, ProjectEngineFactoryProvider, new TestProjectSnapshotManagerDispatcher());
+        var projectManager = new TestProjectSnapshotManager(ProjectEngineFactoryProvider, new TestProjectSnapshotManagerDispatcher());
 
         var projectManagerAccessorMock = new Mock<IProjectSnapshotManagerAccessor>(MockBehavior.Strict);
         projectManagerAccessorMock

src/Razor/test/Microsoft.VisualStudio.LiveShare.Razor.Test/Host/DefaultProjectSnapshotManagerProxyTest.cs

@@ -5,6 +5,7 @@
 
 using System;
 using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.ProjectEngineHost;
@@ -193,32 +194,29 @@ public class DefaultProjectSnapshotManagerProxyTest : ProjectSnapshotManagerDisp
         Assert.Same(state1, state2);
     }
 
-    private class TestProjectSnapshotManager(params IProjectSnapshot[] projects) : ProjectSnapshotManager
+    private class TestProjectSnapshotManager(params IProjectSnapshot[] projects) : IProjectSnapshotManager
     {
         private ImmutableArray<IProjectSnapshot> _projects = projects.ToImmutableArray();
 
-        public override ImmutableArray<IProjectSnapshot> GetProjects() => _projects;
+        public ImmutableArray<IProjectSnapshot> GetProjects() => _projects;
 
-        public override event EventHandler<ProjectChangeEventArgs> Changed;
+        public event EventHandler<ProjectChangeEventArgs> Changed;
 
         public void TriggerChanged(ProjectChangeEventArgs args)
         {
             Changed?.Invoke(this, args);
         }
 
-        public override IProjectSnapshot GetLoadedProject(ProjectKey projectKey)
-        {
-            throw new NotImplementedException();
-        }
+        public IProjectSnapshot GetLoadedProject(ProjectKey projectKey)
+            => throw new NotImplementedException();
 
-        public override ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName)
-        {
-            throw new NotImplementedException();
-        }
+        public ImmutableArray<ProjectKey> GetAllProjectKeys(string projectFileName)
+            => throw new NotImplementedException();
 
-        public override bool IsDocumentOpen(string documentFilePath)
-        {
-            throw new NotImplementedException();
-        }
+        public bool IsDocumentOpen(string documentFilePath)
+            => throw new NotImplementedException();
+
+        public bool TryGetLoadedProject(ProjectKey projectKey, [NotNullWhen(true)] out IProjectSnapshot project)
+            => throw new NotImplementedException();
     }
 }

src/Razor/test/Microsoft.VisualStudio.Razor.IntegrationTests/InProcess/RazorProjectSystemInProcess.cs

@@ -47,9 +47,7 @@ internal partial class RazorProjectSystemInProcess
                 return Task.FromResult(false);
             }
 
-            var project = projectSnapshotManager.GetLoadedProject(projectKeys[0]);
-
-            return Task.FromResult(project is not null);
+            return Task.FromResult(projectSnapshotManager.TryGetLoadedProject(projectKeys[0], out _));
         }, TimeSpan.FromMilliseconds(100), cancellationToken);
     }
 
@@ -61,13 +59,13 @@ internal partial class RazorProjectSystemInProcess
         await Helper.RetryAsync(ct =>
         {
             var projectKeys = projectSnapshotManager.GetAllProjectKeys(projectFilePath);
-            if (projectKeys.Length == 0)
+            if (projectKeys.Length == 0 ||
+                !projectSnapshotManager.TryGetLoadedProject(projectKeys[0], out var project))
             {
                 return Task.FromResult(false);
             }
 
-            var project = projectSnapshotManager.GetLoadedProject(projectKeys[0]);
-            var document = project?.GetDocument(filePath);
+            var document = project.GetDocument(filePath);
 
             return Task.FromResult(document is not null);
         }, TimeSpan.FromMilliseconds(100), cancellationToken);