Add `ProjectPathProvider` abstract for document tracker creation.

- First iteration of live share replaced the document tracker factory entirely; however, this will be prone to breaking changes in the future when me make changes to document tracker to not rely on a file path. To pre-emptively prevent breaking changes I added a project path provider that can be overridden in the live share case. Note that one big difference here between old and new is that instead of being a MEF service implementation for the project path resolution we're bringing that to the Workspace service level.
- Added tests to validate the two flows of the default project path provider.

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

@@ -0,0 +1,41 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.VisualStudio.Text;
+
+namespace Microsoft.VisualStudio.Editor.Razor
+{
+    internal class DefaultProjectPathProvider : ProjectPathProvider
+    {
+        private readonly TextBufferProjectService _projectService;
+
+        public DefaultProjectPathProvider(TextBufferProjectService projectService)
+        {
+            if (projectService == null)
+            {
+                throw new ArgumentNullException(nameof(projectService));
+            }
+
+            _projectService = projectService;
+        }
+
+        public override bool TryGetProjectPath(ITextBuffer textBuffer, out string filePath)
+        {
+            if (textBuffer == null)
+            {
+                throw new ArgumentNullException(nameof(textBuffer));
+            }
+
+            var project = _projectService.GetHostProject(textBuffer);
+            if (project == null)
+            {
+                filePath = null;
+                return false;
+            }
+
+            filePath = _projectService.GetProjectPath(project);
+            return true;
+        }
+    }
+}

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

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.ComponentModel.Composition;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.Razor;
+
+namespace Microsoft.VisualStudio.Editor.Razor
+{
+    [System.Composition.Shared]
+    [ExportWorkspaceService(typeof(ProjectPathProvider), ServiceLayer.Default)]
+    internal class DefaultProjectPathProviderFactory : IWorkspaceServiceFactory
+    {
+        private readonly TextBufferProjectService _projectService;
+
+        [ImportingConstructor]
+        public DefaultProjectPathProviderFactory(TextBufferProjectService projectService)
+        {
+            if (projectService == null)
+            {
+                throw new ArgumentNullException(nameof(projectService));
+            }
+
+            _projectService = projectService;
+        }
+
+        public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
+        {
+            if (workspaceServices == null)
+            {
+                throw new ArgumentNullException(nameof(workspaceServices));
+            }
+
+            return new DefaultProjectPathProvider(_projectService);
+        }
+    }
+}

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

@@ -13,8 +13,8 @@ namespace Microsoft.VisualStudio.Editor.Razor
 {
     internal class DefaultVisualStudioDocumentTrackerFactory : VisualStudioDocumentTrackerFactory
     {
-        private readonly TextBufferProjectService _projectService;
         private readonly ITextDocumentFactoryService _textDocumentFactory;
+        private readonly ProjectPathProvider _projectPathProvider;
         private readonly Workspace _workspace;
         private readonly ImportDocumentManager _importDocumentManager;
         private readonly ForegroundDispatcher _foregroundDispatcher;
@@ -25,7 +25,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
             ForegroundDispatcher foregroundDispatcher,
             ProjectSnapshotManager projectManager,
             WorkspaceEditorSettings workspaceEditorSettings,
-            TextBufferProjectService projectService,
+            ProjectPathProvider projectPathProvider,
             ITextDocumentFactoryService textDocumentFactory,
             ImportDocumentManager importDocumentManager,
             Workspace workspace)
@@ -45,9 +45,9 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 throw new ArgumentNullException(nameof(workspaceEditorSettings));
             }
 
-            if (projectService == null)
+            if (projectPathProvider == null)
             {
-                throw new ArgumentNullException(nameof(projectService));
+                throw new ArgumentNullException(nameof(projectPathProvider));
             }
 
             if (textDocumentFactory == null)
@@ -68,7 +68,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
             _foregroundDispatcher = foregroundDispatcher;
             _projectManager = projectManager;
             _workspaceEditorSettings = workspaceEditorSettings;
-            _projectService = projectService;
+            _projectPathProvider = projectPathProvider;
             _textDocumentFactory = textDocumentFactory;
             _importDocumentManager = importDocumentManager;
             _workspace = workspace;
@@ -87,16 +87,12 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 return null;
             }
 
-            var filePath = textDocument.FilePath;
-            var project = _projectService.GetHostProject(textBuffer);
-            if (project == null)
+            if (!_projectPathProvider.TryGetProjectPath(textBuffer, out var projectPath))
             {
-                Debug.Fail("Text buffer should belong to a project.");
                 return null;
             }
 
-            var projectPath = _projectService.GetProjectPath(project);
-
+            var filePath = textDocument.FilePath;
             var tracker = new DefaultVisualStudioDocumentTracker(_foregroundDispatcher, filePath, projectPath, _projectManager, _workspaceEditorSettings, _workspace, textBuffer, _importDocumentManager);
 
             return tracker;

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

@@ -17,13 +17,11 @@ namespace Microsoft.VisualStudio.Editor.Razor
     internal class DefaultVisualStudioDocumentTrackerFactoryFactory : ILanguageServiceFactory
     {
         private readonly ForegroundDispatcher _foregroundDispatcher;
-        private readonly TextBufferProjectService _projectService;
         private readonly ITextDocumentFactoryService _textDocumentFactory;
 
         [ImportingConstructor]
         public DefaultVisualStudioDocumentTrackerFactoryFactory(
             ForegroundDispatcher foregroundDispatcher,
-            TextBufferProjectService projectService,
             ITextDocumentFactoryService textDocumentFactory)
         {
             if (foregroundDispatcher == null)
@@ -31,18 +29,12 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 throw new ArgumentNullException(nameof(foregroundDispatcher));
             }
 
-            if (projectService == null)
-            {
-                throw new ArgumentNullException(nameof(projectService));
-            }
-
             if (textDocumentFactory == null)
             {
                 throw new ArgumentNullException(nameof(textDocumentFactory));
             }
 
             _foregroundDispatcher = foregroundDispatcher;
-            _projectService = projectService;
             _textDocumentFactory = textDocumentFactory;
         }
 
@@ -57,11 +49,13 @@ namespace Microsoft.VisualStudio.Editor.Razor
             var workspaceEditorSettings = languageServices.GetRequiredService<WorkspaceEditorSettings>();
             var importDocumentManager = languageServices.GetRequiredService<ImportDocumentManager>();
 
+            var projectPathProvider = languageServices.WorkspaceServices.GetRequiredService<ProjectPathProvider>();
+
             return new DefaultVisualStudioDocumentTrackerFactory(
                 _foregroundDispatcher,
                 projectManager,
                 workspaceEditorSettings,
-                _projectService,
+                projectPathProvider,
                 _textDocumentFactory,
                 importDocumentManager,
                 languageServices.WorkspaceServices.Workspace);

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

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.VisualStudio.Text;
+
+namespace Microsoft.VisualStudio.Editor.Razor
+{
+    internal abstract class ProjectPathProvider : IWorkspaceService
+    {
+        public abstract bool TryGetProjectPath(ITextBuffer textBuffer, out string filePath);
+    }
+}

test/Microsoft.VisualStudio.Editor.Razor.Test/DefaultProjectPathProviderTest.cs

@@ -0,0 +1,48 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.VisualStudio.Text;
+using Moq;
+using Xunit;
+
+namespace Microsoft.VisualStudio.Editor.Razor
+{
+    public class DefaultProjectPathProviderTest
+    {
+        [Fact]
+        public void TryGetProjectPath_ReturnsFalseIfNoProject()
+        {
+            // Arrange
+            var projectPathProvider = new DefaultProjectPathProvider(Mock.Of<TextBufferProjectService>());
+            var textBuffer = Mock.Of<ITextBuffer>();
+
+            // Act
+            var result = projectPathProvider.TryGetProjectPath(textBuffer, out var filePath);
+
+            // Assert
+            Assert.False(result);
+            Assert.Null(filePath);
+        }
+
+        [Fact]
+        public void TryGetProjectPath_ReturnsTrueIfProject()
+        {
+            // Arrange
+            var expectedProjectPath = "/my/project/path.csproj";
+            var projectService = new Mock<TextBufferProjectService>();
+            projectService.Setup(service => service.GetHostProject(It.IsAny<ITextBuffer>()))
+                .Returns(new object());
+            projectService.Setup(service => service.GetProjectPath(It.IsAny<object>()))
+                .Returns(expectedProjectPath);
+            var projectPathProvider = new DefaultProjectPathProvider(projectService.Object);
+            var textBuffer = Mock.Of<ITextBuffer>();
+
+            // Act
+            var result = projectPathProvider.TryGetProjectPath(textBuffer, out var filePath);
+
+            // Assert
+            Assert.True(result);
+            Assert.Equal(expectedProjectPath, filePath);
+        }
+    }
+}