Fix file header insertion before a blank line

Fixes #2415

Author: sharwell

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

@@ -211,7 +211,7 @@ private static SyntaxNode ReplaceHeader(Document document, SyntaxNode root, Styl
             bool onBlankLine = false;
             bool inCopyright = isMalformedHeader;
             int? copyrightTriviaIndex = null;
-            var removalList = new System.Collections.Generic.List<int>();
+            var removalList = new List<int>();
             var leadingSpaces = string.Empty;
             string possibleLeadingSpaces = string.Empty;
 
@@ -351,7 +351,34 @@ private static SyntaxNode AddHeader(Document document, SyntaxNode root, string n
             string newLineText = document.Project.Solution.Workspace.Options.GetOption(FormattingOptions.NewLine, LanguageNames.CSharp);
             var newLineTrivia = SyntaxFactory.EndOfLine(newLineText);
             var newTrivia = CreateNewHeader("//", name, settings, newLineText).Add(newLineTrivia).Add(newLineTrivia);
-            newTrivia = newTrivia.AddRange(root.GetLeadingTrivia());
+
+            // Skip blank lines already at the beginning of the document, since we add our own
+            SyntaxTriviaList leadingTrivia = root.GetLeadingTrivia();
+            int skipCount = 0;
+            for (int i = 0; i < leadingTrivia.Count; i++)
+            {
+                bool done = false;
+                switch (leadingTrivia[i].Kind())
+                {
+                case SyntaxKind.WhitespaceTrivia:
+                    break;
+
+                case SyntaxKind.EndOfLineTrivia:
+                    skipCount = i + 1;
+                    break;
+
+                default:
+                    done = true;
+                    break;
+                }
+
+                if (done)
+                {
+                    break;
+                }
+            }
+
+            newTrivia = newTrivia.AddRange(leadingTrivia.RemoveRange(0, skipCount));
 
             return root.WithLeadingTrivia(newTrivia);
         }

StyleCop.Analyzers/StyleCop.Analyzers.Test/DocumentationRules/NoXmlFileHeaderUnitTests.cs

@@ -50,6 +50,101 @@ public virtual async Task TestNoFileHeaderAsync()
             var fixedCode = @"// Copyright (c) FooCorp. All rights reserved.
 // Licensed under the ??? license. See LICENSE file in the project root for full license information.
 
+namespace Foo
+{
+}
+";
+
+            var expectedDiagnostic = this.CSharpDiagnostic(FileHeaderAnalyzers.SA1633DescriptorMissing).WithLocation(1, 1);
+            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);
+        }
+
+        /// <summary>
+        /// Verifies that the analyzer will report <see cref="FileHeaderAnalyzers.SA1633DescriptorMissing"/> for
+        /// projects not using XML headers when the file is completely missing a header.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        [WorkItem(2415, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2415")]
+        public virtual async Task TestNoFileHeaderWithUsingDirectiveAsync()
+        {
+            var testCode = @"using System;
+
+namespace Foo
+{
+}
+";
+            var fixedCode = @"// Copyright (c) FooCorp. All rights reserved.
+// Licensed under the ??? license. See LICENSE file in the project root for full license information.
+
+using System;
+
+namespace Foo
+{
+}
+";
+
+            var expectedDiagnostic = this.CSharpDiagnostic(FileHeaderAnalyzers.SA1633DescriptorMissing).WithLocation(1, 1);
+            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);
+        }
+
+        /// <summary>
+        /// Verifies that the analyzer will report <see cref="FileHeaderAnalyzers.SA1633DescriptorMissing"/> for
+        /// projects not using XML headers when the file is completely missing a header.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        [WorkItem(2415, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2415")]
+        public virtual async Task TestNoFileHeaderWithBlankLineAndUsingDirectiveAsync()
+        {
+            var testCode = @"
+using System;
+
+namespace Foo
+{
+}
+";
+            var fixedCode = @"// Copyright (c) FooCorp. All rights reserved.
+// Licensed under the ??? license. See LICENSE file in the project root for full license information.
+
+using System;
+
+namespace Foo
+{
+}
+";
+
+            var expectedDiagnostic = this.CSharpDiagnostic(FileHeaderAnalyzers.SA1633DescriptorMissing).WithLocation(1, 1);
+            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);
+        }
+
+        /// <summary>
+        /// Verifies that the analyzer will report <see cref="FileHeaderAnalyzers.SA1633DescriptorMissing"/> for
+        /// projects not using XML headers when the file is completely missing a header.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous unit test.</returns>
+        [Fact]
+        [WorkItem(2415, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/2415")]
+        public virtual async Task TestNoFileHeaderWithWhitespaceLineAsync()
+        {
+            var testCode = "    " + @"
+using System;
+
+namespace Foo
+{
+}
+";
+            var fixedCode = @"// Copyright (c) FooCorp. All rights reserved.
+// Licensed under the ??? license. See LICENSE file in the project root for full license information.
+
+using System;
+
 namespace Foo
 {
 }