Properly handle lack of editorconfig file for naming styles (#16413)

We now return false if we get an empty set of naming styles.

src/Workspaces/Core/Portable/Options/EditorConfigStorageLocation.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics.Analyzers.NamingStyles;
 using static Microsoft.CodeAnalysis.CodeStyle.CodeStyleHelpers;
@@ -17,7 +18,7 @@ internal sealed class EditorConfigStorageLocation : OptionStorageLocation
 
         private Func<string, Type, object> _parseValue;
 
-        private Func<IReadOnlyDictionary<string, object>, Type, object> _parseDictionary;
+        private Func<IReadOnlyDictionary<string, object>, Type, (object result, bool succeeded)> _tryParseDictionary;
 
         public bool TryParseReadonlyDictionary(IReadOnlyDictionary<string, object> allRawConventions, Type type, out object result)
         {
@@ -29,10 +30,11 @@ public bool TryParseReadonlyDictionary(IReadOnlyDictionary<string, object> allRa
                     return true;
                 }
             }
-            else if (_parseDictionary != null)
+            else if (_tryParseDictionary != null)
             {
-                result = _parseDictionary(allRawConventions, type);
-                return true;
+                var tuple = _tryParseDictionary(allRawConventions, type);
+                result = tuple.result;
+                return tuple.succeeded;
             }
 
             result = null;
@@ -75,11 +77,19 @@ public EditorConfigStorageLocation(string keyName, Func<string, object> parseVal
         public EditorConfigStorageLocation()
         {
             // If the user didn't pass a keyName assume we need to parse the entire dictionary
-            _parseDictionary = (dictionary, type) =>
+            _tryParseDictionary = (dictionary, type) =>
             {
                 if (type == typeof(NamingStylePreferences))
                 {
-                    return EditorConfigNamingStyleParser.GetNamingStylesFromDictionary(dictionary);
+                    var result = EditorConfigNamingStyleParser.GetNamingStylesFromDictionary(dictionary);
+                    if (!result.NamingRules.Any() &&
+                        !result.NamingStyles.Any() &&
+                        !result.SymbolSpecifications.Any())
+                    {
+                        return (result: result, succeeded: false);
+                    }
+
+                    return (result: result, succeeded: true);
                 }
                 else
                 {
@@ -88,10 +98,10 @@ public EditorConfigStorageLocation()
             };
         }
 
-        public EditorConfigStorageLocation(Func<IReadOnlyDictionary<string, object>, object> parseDictionary)
+        public EditorConfigStorageLocation(Func<IReadOnlyDictionary<string, object>, (object result, bool succeeded)> tryParseDictionary)
         {
             // If we're explicitly given a parsing function we can throw away the type when parsing
-            _parseDictionary = (dictionary, type) => parseDictionary(dictionary);
+            _tryParseDictionary = (dictionary, type) => tryParseDictionary(dictionary);
         }
     }
 }

src/Workspaces/CoreTest/EditorConfigStorageLocation/EditorConfigStorageLocationTests.cs

+// 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;
+using System.Collections.Generic;
+using Microsoft.CodeAnalysis.Diagnostics.Analyzers.NamingStyles;
+using Microsoft.CodeAnalysis.Options;
+using Xunit;
+
+namespace Microsoft.CodeAnalysis.UnitTests.EditorConfig.StorageLocation
+{
+    public class EditorConfigStorageLocationTests
+    {
+        [Fact]
+        public static void TestEmptyDictionaryReturnFalse()
+        {
+            var editorConfigStorageLocation = new EditorConfigStorageLocation();
+            var result = editorConfigStorageLocation.TryParseReadonlyDictionary(new Dictionary<string, object>(), typeof(NamingStylePreferences), out var @object);
+            Assert.False(result, "Expected TryParseReadonlyDictionary to return 'false' for empty dictionary");
+        }
+
+        [Fact]
+        public static void TestObjectTypeThrowsNotSupportedException()
+        {
+            var editorConfigStorageLocation = new EditorConfigStorageLocation();
+            Assert.Throws<NotSupportedException>(() =>
+            {
+                editorConfigStorageLocation.TryParseReadonlyDictionary(new Dictionary<string, object>(), typeof(object), out var @object);
+            });
+        }
+    }
+}

src/Workspaces/CoreTest/ServicesTest.csproj

@@ -72,6 +72,7 @@
   <ItemGroup>
     <Compile Include="CodeStyle\EditorConfigCodeStyleParserTests.cs" />
     <Compile Include="DependentTypeFinderTests.cs" />
+    <Compile Include="EditorConfigStorageLocation\EditorConfigStorageLocationTests.cs" />
     <Compile Include="Editting\SyntaxEditorTests.cs" />
     <Compile Include="Execution\Extensions.cs" />
     <Compile Include="Execution\SnapshotSerializationTestBase.cs" />