Fix duplicate decoration in fix for SA1638

When running the fix for SA1638, the header decoration is duplicated

Author: zitzltho

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/DocumentationRules/FileHeaderCodeFixProvider.cs

@@ -4,6 +4,7 @@
 namespace StyleCop.Analyzers.DocumentationRules
 {
     using System;
+    using System.Collections.Generic;
     using System.Collections.Immutable;
     using System.Composition;
     using System.Text;
@@ -212,6 +213,9 @@ private static SyntaxNode ReplaceHeader(Document document, SyntaxNode root, Styl
             var leadingSpaces = string.Empty;
             string possibleLeadingSpaces = string.Empty;
 
+            // remove header decoration lines, they will be re-generated
+            trivia = RemoveHeaderDecorationLines(trivia, settings);
+
             // Need to do this with index so we get the line endings correct.
             for (int i = 0; i < trivia.Count; i++)
             {
@@ -386,5 +390,35 @@ private static string GetCopyrightText(string prefixWithLeadingSpaces, string co
             copyrightText = copyrightText.Replace("\r\n", "\n");
             return string.Join(newLineText + prefixWithLeadingSpaces + " ", copyrightText.Split('\n')).Replace(prefixWithLeadingSpaces + " " + newLineText, prefixWithLeadingSpaces + newLineText);
         }
+
+        private static SyntaxTriviaList RemoveHeaderDecorationLines(SyntaxTriviaList trivia, StyleCopSettings settings)
+        {
+            if (!string.IsNullOrEmpty(settings.DocumentationRules.HeaderDecoration))
+            {
+                var decorationRemovalList = new List<int>();
+                for (int i = 0; i < trivia.Count; i++)
+                {
+                    var triviaLine = trivia[i];
+                    if (triviaLine.Kind() == SyntaxKind.SingleLineCommentTrivia && triviaLine.ToFullString().Contains(settings.DocumentationRules.HeaderDecoration))
+                    {
+                        decorationRemovalList.Add(i);
+
+                        // also remove the line break
+                        if (i + 1 < trivia.Count && trivia[i + 1].Kind() == SyntaxKind.EndOfLineTrivia)
+                        {
+                            decorationRemovalList.Add(i + 1);
+                        }
+                    }
+                }
+
+                // Remove decoration lines in reverse order.
+                for (int i = decorationRemovalList.Count - 1; i >= 0; i--)
+                {
+                    trivia = trivia.RemoveAt(decorationRemovalList[i]);
+                }
+            }
+
+            return trivia;
+        }
     }
 }

StyleCop.Analyzers/StyleCop.Analyzers.Test/DocumentationRules/SA1638UnitTests.cs

@@ -14,6 +14,20 @@ namespace StyleCop.Analyzers.Test.DocumentationRules
     /// </summary>
     public class SA1638UnitTests : FileHeaderTestBase
     {
+        private const string DecoratedXmlMultiLineHeaderTestSettings = @"
+{
+  ""settings"": {
+    ""documentationRules"": {
+      ""companyName"": ""FooCorp"",
+      ""copyrightText"": ""  Copyright (c) {companyName}. All rights reserved."",
+      ""headerDecoration"": ""-----------------------------------------------------------------------"",
+    }
+  }
+}
+";
+
+        private bool useDecoratedXmlMultiLineHeaderTestSettings;
+
         /// <summary>
         /// Verifies that a file header with a mismatching file attribute in the copyright element will produce the expected diagnostic message.
         /// </summary>
@@ -44,9 +58,56 @@ namespace Bar
             await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
         }
 
+        /// <summary>
+        /// Verifies that a file header with a mismatching file attribute in the copyright element will produce the expected diagnostic message.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        public async Task TestCopyrightElementWithMismatchingFileAttributeAndDecorationAsync()
+        {
+            var testCode = @"// -----------------------------------------------------------------------
+// <copyright file=""wrongfile.cs"" company=""FooCorp"">
+//   Copyright (c) FooCorp. All rights reserved.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Bar
+{
+}
+";
+            var fixedCode = @"// -----------------------------------------------------------------------
+// <copyright file=""Test0.cs"" company=""FooCorp"">
+//   Copyright (c) FooCorp. All rights reserved.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Bar
+{
+}
+";
+
+            this.useDecoratedXmlMultiLineHeaderTestSettings = true;
+
+            var expectedDiagnostic = this.CSharpDiagnostic(FileHeaderAnalyzers.SA1638Descriptor).WithLocation(2, 4);
+            await this.VerifyCSharpDiagnosticAsync(testCode, expectedDiagnostic, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpDiagnosticAsync(fixedCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+            await this.VerifyCSharpFixAsync(testCode, fixedCode, cancellationToken: CancellationToken.None).ConfigureAwait(false);
+        }
+
         protected override CodeFixProvider GetCSharpCodeFixProvider()
         {
             return new FileHeaderCodeFixProvider();
         }
+
+        /// <inheritdoc/>
+        protected override string GetSettings()
+        {
+            if (this.useDecoratedXmlMultiLineHeaderTestSettings)
+            {
+                return DecoratedXmlMultiLineHeaderTestSettings;
+            }
+
+            return base.GetSettings();
+        }
     }
 }