Merge pull request dotnet#33264 from jasonmalinowski/fix-document.fol…

…ders-not-populating

Compute relative folder information if we aren't given it

src/VisualStudio/CSharp/Test/ProjectSystemShim/LegacyProject/SourceFileHandlingTests.cs

@@ -1,7 +1,9 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System.IO;
 using System.Linq;
 using Microsoft.CodeAnalysis.Test.Utilities;
+using Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem.Interop;
 using Microsoft.VisualStudio.LanguageServices.UnitTests.ProjectSystemShim.Framework;
 using Roslyn.Test.Utilities;
 using Xunit;
@@ -29,5 +31,71 @@ public void IgnoreAdditionsOfXomlFiles()
                 project.OnSourceFileRemoved("Goo.xoml");
             }
         }
+
+        [WpfFact]
+        [Trait(Traits.Feature, Traits.Features.ProjectSystemShims)]
+        public void AddFileExWithLinkPathUsesThatAsAFolder()
+        {
+            using (var environment = new TestEnvironment())
+            {
+                var project = CSharpHelpers.CreateCSharpProject(environment, "Test");
+
+                project.AddFileEx(@"C:\Cat.cs", linkMetadata: @"LinkFolder\Cat.cs");
+
+                var document = environment.Workspace.CurrentSolution.Projects.Single().Documents.Single();
+
+                Assert.Equal(new[] { "LinkFolder" }, document.Folders);
+            }
+        }
+
+        [WpfFact]
+        [Trait(Traits.Feature, Traits.Features.ProjectSystemShims)]
+        public void AddFileExWithLinkPathWithoutFolderWorksCorrectly()
+        {
+            using (var environment = new TestEnvironment())
+            {
+                var project = CSharpHelpers.CreateCSharpProject(environment, "Test");
+
+                project.AddFileEx(@"C:\Cat.cs", linkMetadata: @"Dog.cs");
+
+                var document = environment.Workspace.CurrentSolution.Projects.Single().Documents.Single();
+
+                Assert.Empty(document.Folders);
+            }
+        }
+
+        [WpfFact]
+        [Trait(Traits.Feature, Traits.Features.ProjectSystemShims)]
+        public void AddFileExWithNoLinkPathComputesEmptyFolder()
+        {
+            using (var environment = new TestEnvironment())
+            {
+                var project = CSharpHelpers.CreateCSharpProject(environment, "Test");
+                var projectFolder = Path.GetDirectoryName(environment.Workspace.CurrentSolution.Projects.Single().FilePath);
+
+                project.AddFileEx(Path.Combine(projectFolder, "Cat.cs"), null);
+
+                var document = environment.Workspace.CurrentSolution.Projects.Single().Documents.Single();
+
+                Assert.Empty(document.Folders);
+            }
+        }
+
+        [WpfFact]
+        [Trait(Traits.Feature, Traits.Features.ProjectSystemShims)]
+        public void AddFileExWithNoLinkPathComputesRelativeFolderPath()
+        {
+            using (var environment = new TestEnvironment())
+            {
+                var project = CSharpHelpers.CreateCSharpProject(environment, "Test");
+                var projectFolder = Path.GetDirectoryName(environment.Workspace.CurrentSolution.Projects.Single().FilePath);
+
+                project.AddFileEx(Path.Combine(projectFolder, "RelativeFolder", "Cat.cs"), null);
+
+                var document = environment.Workspace.CurrentSolution.Projects.Single().Documents.Single();
+
+                Assert.Equal(new[] { "RelativeFolder" }, document.Folders);
+            }
+        }
     }
 }

src/VisualStudio/Core/Def/Implementation/ProjectSystem/Legacy/AbstractLegacyProject.cs

@@ -31,6 +31,13 @@ internal abstract partial class AbstractLegacyProject : ForegroundThreadAffiniti
         protected IProjectCodeModel ProjectCodeModel { get; set; }
         protected VisualStudioWorkspace Workspace { get; }
 
+        /// <summary>
+        /// The path to the directory of the project. Read-only, since although you can rename
+        /// a project in Visual Studio you can't change the folder of a project without an
+        /// unload/reload.
+        /// </summary>
+        private readonly string _projectDirectory = null;
+
         private static readonly char[] PathSeparatorCharacters = { Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar };
 
         #region Mutable fields that should only be used from the UI thread
@@ -64,6 +71,11 @@ public AbstractLegacyProject(
                 projectFilePath = null;
             }
 
+            if (projectFilePath != null)
+            {
+                _projectDirectory = Path.GetDirectoryName(projectFilePath);
+            }
+
             var projectFactory = componentModel.GetService<VisualStudioProjectFactory>();
             VisualStudioProject = projectFactory.CreateAndAddToWorkspace(
                 projectSystemName,
@@ -163,7 +175,13 @@ protected void AddFile(
             if (!string.IsNullOrEmpty(linkMetadata))
             {
                 var linkFolderPath = Path.GetDirectoryName(linkMetadata);
-                folders = linkFolderPath.Split(PathSeparatorCharacters).ToImmutableArray();
+                folders = linkFolderPath.Split(PathSeparatorCharacters, StringSplitOptions.RemoveEmptyEntries).ToImmutableArray();
+            }
+            else if (!string.IsNullOrEmpty(VisualStudioProject.FilePath))
+            {
+                var relativePath = PathUtilities.GetRelativePath(_projectDirectory, filename);
+                var relativePathParts = relativePath.Split(PathSeparatorCharacters);
+                folders = ImmutableArray.Create(relativePathParts, start: 0, length: relativePathParts.Length - 1);
             }
 
             VisualStudioProject.AddSourceFile(filename, sourceCodeKind, folders);