Allow Solution Filter files to be passed as the workspace path

src/MSBuild/MSBuildWorkspaceFinder.cs

@@ -60,7 +60,7 @@ public static (bool isSolution, string workspacePath) FindWorkspace(string searc
         private static (bool isSolution, string workspacePath) FindFile(string workspacePath)
         {
             var workspaceExtension = Path.GetExtension(workspacePath);
-            var isSolution = workspaceExtension.Equals(".sln", StringComparison.OrdinalIgnoreCase);
+            var isSolution = workspaceExtension.Equals(".sln", StringComparison.OrdinalIgnoreCase) || workspaceExtension.Equals(".slnf", StringComparison.OrdinalIgnoreCase);
             var isProject = !isSolution
                 && workspaceExtension.EndsWith("proj", StringComparison.OrdinalIgnoreCase)
                 && !workspaceExtension.Equals(DnxProjectExtension, StringComparison.OrdinalIgnoreCase);
@@ -81,7 +81,8 @@ private static (bool isSolution, string workspacePath) FindFile(string workspace
             return (isSolution, workspacePath);
         }
 
-        private static IEnumerable<string> FindSolutionFiles(string basePath) => Directory.EnumerateFileSystemEntries(basePath, "*.sln", SearchOption.TopDirectoryOnly);
+        private static IEnumerable<string> FindSolutionFiles(string basePath) => Directory.EnumerateFileSystemEntries(basePath, "*.sln", SearchOption.TopDirectoryOnly)
+            .Concat(Directory.EnumerateFileSystemEntries(basePath, "*.slnf", SearchOption.TopDirectoryOnly));
 
         private static IEnumerable<string> FindProjectFiles(string basePath) => Directory.EnumerateFileSystemEntries(basePath, "*.*proj", SearchOption.TopDirectoryOnly)
                     .Where(f => !DnxProjectExtension.Equals(Path.GetExtension(f), StringComparison.OrdinalIgnoreCase));

tests/CodeFormatterTests.cs

@@ -36,6 +36,8 @@ public class CodeFormatterTests
         private static readonly string s_codeStyleSolutionPath = Path.Combine("for_code_formatter", "codestyle_solution");
         private static readonly string s_codeStyleSolutionFilePath = Path.Combine(s_codeStyleSolutionPath, "codestyle_solution.sln");
 
+        private static readonly string s_codeStyleSolutionFilterFilePath = Path.Combine(s_codeStyleSolutionPath, "codestyle_solution_filter.slnf");
+
         private static readonly string s_analyzersSolutionPath = Path.Combine("for_code_formatter", "analyzers_solution");
         private static readonly string s_analyzersSolutionFilePath = Path.Combine(s_analyzersSolutionPath, "analyzers_solution.sln");
 
@@ -455,6 +457,24 @@ public async Task FilesFormattedInCodeStyleSolution_WhenFixingCodeStyleWarnings(
                 codeStyleSeverity: DiagnosticSeverity.Warning);
         }
 
+        [MSBuildFact]
+        public async Task FilesFormattedInCodeStyleSolutionFilter_WhenFixingCodeStyleWarnings()
+        {
+            var restoreExitCode = await NuGetHelper.PerformRestore(s_codeStyleSolutionFilterFilePath, _output);
+            Assert.Equal(0, restoreExitCode);
+
+            await TestFormatWorkspaceAsync(
+                s_codeStyleSolutionFilterFilePath,
+                include: EmptyFilesList,
+                exclude: EmptyFilesList,
+                includeGenerated: false,
+                expectedExitCode: 0,
+                expectedFilesFormatted: 1,
+                expectedFileCount: 3,
+                fixCategory: FixCategory.Whitespace | FixCategory.CodeStyle,
+                codeStyleSeverity: DiagnosticSeverity.Warning);
+        }
+
         [MSBuildFact]
         public async Task NoFilesFormattedInAnalyzersSolution_WhenNotFixingAnalyzers()
         {
@@ -510,9 +530,9 @@ public async Task FilesFormattedInAnalyzersSolution_WhenFixingAnalyzerErrors()
             }
             else
             {
-                workspaceType = workspacePath.EndsWith(".sln")
-                    ? WorkspaceType.Solution
-                    : WorkspaceType.Project;
+                workspaceType = workspacePath.EndsWith("proj")
+                    ? WorkspaceType.Project
+                    : WorkspaceType.Solution;
             }
 
             var logger = new TestLogger();

tests/projects/for_code_formatter/codestyle_solution/codestyle_solution_filter.slnf

@@ -0,0 +1,8 @@
+{
+  "solution": {
+    "path": "codestyle_solution.sln",
+    "projects": [
+      ".\\library\\library.csproj"
+    ]
+  }
+}