Fix SA1127 code fix indenting when additional preceding trivia is present (#1652)

Author: nbarbettini

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/ReadabilityRules/SA1127CodeFixProvider.cs

@@ -6,6 +6,7 @@ namespace StyleCop.Analyzers.ReadabilityRules
     using System.Collections.Generic;
     using System.Collections.Immutable;
     using System.Composition;
+    using System.Linq;
     using System.Threading;
     using System.Threading.Tasks;
     using Helpers;
@@ -88,18 +89,12 @@ private static async Task<Document> GetTransformedDocumentAsync(Document documen
 
         private static string GetParentIndentation(SyntaxToken token)
         {
-            var parentLine = token.Parent.Parent;
-            var parentIndentation = string.Empty;
-            var parentTrivia = parentLine.GetLeadingTrivia();
-            foreach (var trivia in parentTrivia)
-            {
-                if (trivia.IsKind(SyntaxKind.WhitespaceTrivia))
-                {
-                    parentIndentation += trivia.ToString();
-                }
-            }
+            var parentTrivia = token.Parent.Parent.GetLeadingTrivia();
 
-            return parentIndentation;
+            return parentTrivia
+                .Where(t => t.IsKind(SyntaxKind.WhitespaceTrivia))
+                .LastOrDefault()
+                .ToString();
         }
 
         // This function will remove any unnecessary whitespace or end-of-line trivia from a token.

StyleCop.Analyzers/StyleCop.Analyzers.Test/ReadabilityRules/SA1127UnitTests.cs

@@ -128,6 +128,66 @@ private void Method<T>(
             await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
         }
 
+        /// <summary>
+        /// This is a regression test for DotNetAnalyzers/StyleCopAnalyzers#1652:
+        /// https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/1652
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        public async Task TestViolationWithMethodDeclarationAndXmlCommentsAsync()
+        {
+            var testCode = $@"
+class Foo
+{{
+    /// <summary>Foo</summary>
+    /// <typeparam name=""T"">The type.</typeparam>
+    private void Method<T>() where T : class {{ }}
+}}";
+            var fixedCode = $@"
+class Foo
+{{
+    /// <summary>Foo</summary>
+    /// <typeparam name=""T"">The type.</typeparam>
+    private void Method<T>()
+        where T : class
+    {{ }}
+}}";
+            var expected = this.CSharpDiagnostic().WithLocation(6, 30);
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// This is a regression test for DotNetAnalyzers/StyleCopAnalyzers#1652:
+        /// https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/1652
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        public async Task TestViolationWithMethodDeclarationRegionDirectiveAsync()
+        {
+            var testCode = $@"
+class Foo
+{{
+    #region Test
+    private void Method<T>() where T : class {{ }}
+    #endregion
+}}";
+            var fixedCode = $@"
+class Foo
+{{
+    #region Test
+    private void Method<T>()
+        where T : class
+    {{ }}
+    #endregion
+}}";
+            var expected = this.CSharpDiagnostic().WithLocation(5, 30);
+            await this.VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task TestViolationWithExpressionBodiedMethodDeclarationAsync()
         {