Merge pull request #1866 from vweijsters/fix-1861

SA1306 now ignores leading underscores.

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/NamingRules/RenameToLowerCaseCodeFixProvider.cs

@@ -51,6 +51,7 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                 }
 
                 var originalName = token.ValueText;
+
                 var baseName = originalName.TrimStart('_');
                 if (baseName.Length == 0)
                 {
@@ -60,7 +61,7 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
 
                 baseName = char.ToLower(baseName[0]) + baseName.Substring(1);
                 int underscoreCount = originalName.Length - baseName.Length;
-                var newName = baseName;
+
                 var memberSyntax = RenameHelper.GetParentDeclaration(token);
 
                 SemanticModel semanticModel = await document.GetSemanticModelAsync(context.CancellationToken).ConfigureAwait(false);
@@ -71,11 +72,15 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                     continue;
                 }
 
+                // preserve the underscores, but only for fields.
+                var prefix = declaredSymbol.Kind == SymbolKind.Field ? originalName.Substring(0, underscoreCount) : string.Empty;
+                var newName = prefix + baseName;
+
                 int index = 0;
                 while (!await RenameHelper.IsValidNewMemberNameAsync(semanticModel, declaredSymbol, newName, context.CancellationToken).ConfigureAwait(false))
                 {
                     index++;
-                    newName = baseName + index;
+                    newName = prefix + baseName + index;
                 }
 
                 context.RegisterCodeFix(

StyleCop.Analyzers/StyleCop.Analyzers.Test/NamingRules/SA1306UnitTests.cs

@@ -135,12 +135,27 @@ public async Task TestThatDiagnosticIsReported_SingleFieldAsync(string modifiers
 string car;
 {0}
 string Dar;
+{0}
+string _ear;
+{0}
+string _Far;
+{0}
+string __gar;
+{0}
+string __Har;
+{0}
+string ___iar;
+{0}
+string ___Jar;
 }}";
 
             DiagnosticResult[] expected =
                 {
                     this.CSharpDiagnostic().WithArguments("Bar").WithLocation(4, 8),
-                    this.CSharpDiagnostic().WithArguments("Dar").WithLocation(8, 8)
+                    this.CSharpDiagnostic().WithArguments("Dar").WithLocation(8, 8),
+                    this.CSharpDiagnostic().WithArguments("_Far").WithLocation(12, 8),
+                    this.CSharpDiagnostic().WithArguments("__Har").WithLocation(16, 8),
+                    this.CSharpDiagnostic().WithArguments("___Jar").WithLocation(20, 8),
                 };
 
             await this.VerifyCSharpDiagnosticAsync(string.Format(testCode, modifiers), expected, CancellationToken.None).ConfigureAwait(false);
@@ -153,6 +168,18 @@ public async Task TestThatDiagnosticIsReported_SingleFieldAsync(string modifiers
 string car;
 {0}
 string dar;
+{0}
+string _ear;
+{0}
+string _far;
+{0}
+string __gar;
+{0}
+string __har;
+{0}
+string ___iar;
+{0}
+string ___jar;
 }}";
 
             await this.VerifyCSharpDiagnosticAsync(string.Format(fixedCode, modifiers), EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
@@ -193,28 +220,62 @@ public async Task TestThatDiagnosticIsReported_MultipleFieldsAsync(string modifi
         }
 
         [Fact]
-        public async Task TestFieldStartingWithAnUnderscoreAsync()
+        public async Task TestFieldStartingWithLetterAsync()
         {
-            // Makes sure SA1306 is not reported for fields starting with an underscore
             var testCode = @"public class Foo
 {
-    public string _bar = ""baz"";
+    public string bar = ""baz"";
 }";
 
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
         [Fact]
-        public async Task TestFieldStartingWithLetterAsync()
+        public async Task TestFieldWithAllUnderscoresAsync()
         {
             var testCode = @"public class Foo
 {
-    public string bar = ""baz"";
+    private string _ = ""bar"";
+    private string __ = ""baz"";
+    private string ___ = ""qux"";
 }";
 
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        public async Task TestFieldWithTrailingUnderscoreAsync()
+        {
+            var testCode = @"public class Foo
+{
+    private string someVar_ = ""bar"";
+}";
+
+            await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+        }
+
+        [Fact]
+        public async Task TestFieldWithCodefixRenameConflictAsync()
+        {
+            var testCode = @"public class Foo
+{
+    private string _test = ""test1"";
+    private string _Test = ""test2"";
+}";
+
+            var fixedTestCode = @"public class Foo
+{
+    private string _test = ""test1"";
+    private string _test1 = ""test2"";
+}";
+
+            var expected = this.CSharpDiagnostic().WithArguments("_Test").WithLocation(4, 20);
+
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedTestCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedTestCode).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task TestFieldPlacedInsideNativeMethodsClassAsync()
         {

StyleCop.Analyzers/StyleCop.Analyzers/NamingRules/SA1306FieldNamesMustBeginWithLowerCaseLetter.cs

@@ -114,14 +114,25 @@ private static void HandleFieldDeclaration(SyntaxNodeAnalysisContext context)
                 }
 
                 string name = identifier.ValueText;
-                if (string.IsNullOrEmpty(name) || char.IsLower(name[0]))
+                if (string.IsNullOrEmpty(name))
                 {
                     continue;
                 }
 
-                if (name[0] == '_')
+                var index = 0;
+                while ((index < name.Length) && name[index] == '_')
+                {
+                    index++;
+                }
+
+                if (index == name.Length)
+                {
+                    // ignore fields with all underscores
+                    continue;
+                }
+
+                if (char.IsLower(name, index))
                 {
-                    // `_foo` is handled by SA1309
                     continue;
                 }