Fix multiline copyright header rule

Author: krwq

src/Microsoft.DotNet.CodeFormatting.Tests/Rules/CopyrightHeaderRuleTests.cs

@@ -29,6 +29,25 @@ class C
 
             var expected = @"// test
 
+class C
+{
+}";
+            Verify(source, expected);
+
+        }
+
+        [Fact]
+        public void CSharpSimpleMultiline()
+        {
+            _options.CopyrightHeader = ImmutableArray.Create("test1", "test2");
+            var source = @"
+class C
+{
+}";
+
+            var expected = @"// test1
+// test2
+
 class C
 {
 }";
@@ -48,6 +67,62 @@ class C
 
             var expected = @"// test
 
+class C
+{
+}";
+            Verify(source, expected);
+
+        }
+
+        [Fact]
+        public void CSharpPreserveExistingMultiline()
+        {
+            _options.CopyrightHeader = ImmutableArray.Create("test1", "test2");
+            var source = @"// test1
+// test2
+
+class C
+{
+}";
+
+            var expected = @"// test1
+// test2
+
+class C
+{
+}";
+            Verify(source, expected);
+
+        }
+
+        [Fact]
+        public void CSharpPreserveExistingWithCommentMultiline()
+        {
+            _options.CopyrightHeader = ImmutableArray.Create("test1", "test2");
+            var source = @"// test1
+// test2
+
+
+
+
+
+// test3
+
+
+class C
+{
+}";
+
+            var expected = @"// test1
+// test2
+
+
+
+
+
+// test3
+
+
 class C
 {
 }";

src/Microsoft.DotNet.CodeFormatting/Rules/CopyrightHeaderRule.CSharp.cs

@@ -32,11 +32,14 @@ protected override bool IsLineComment(SyntaxTrivia trivia)
                 return trivia.Kind() == SyntaxKind.SingleLineCommentTrivia;
             }
 
-            protected override bool IsWhiteSpaceOrNewLine(SyntaxTrivia trivia)
+            protected override bool IsWhitespace(SyntaxTrivia trivia)
             {
-                return
-                    trivia.Kind() == SyntaxKind.WhitespaceTrivia ||
-                    trivia.Kind() == SyntaxKind.EndOfLineTrivia;
+                return trivia.Kind() == SyntaxKind.WhitespaceTrivia;
+            }
+
+            protected override bool IsNewLine(SyntaxTrivia trivia)
+            {
+                return trivia.Kind() == SyntaxKind.EndOfLineTrivia;
             }
 
             protected override SyntaxTrivia CreateLineComment(string commentText)

src/Microsoft.DotNet.CodeFormatting/Rules/CopyrightHeaderRule.VisualBasic.cs

@@ -31,11 +31,14 @@ protected override bool IsLineComment(SyntaxTrivia trivia)
                 return trivia.Kind() == SyntaxKind.CommentTrivia;
             }
 
-            protected override bool IsWhiteSpaceOrNewLine(SyntaxTrivia trivia)
+            protected override bool IsWhitespace(SyntaxTrivia trivia)
             {
-                return
-                    trivia.Kind() == SyntaxKind.WhitespaceTrivia ||
-                    trivia.Kind() == SyntaxKind.EndOfLineTrivia;
+                return trivia.Kind() == SyntaxKind.WhitespaceTrivia;
+            }
+
+            protected override bool IsNewLine(SyntaxTrivia trivia)
+            {
+                return trivia.Kind() == SyntaxKind.EndOfLineTrivia;
             }
 
             protected override SyntaxTrivia CreateLineComment(string commentText)

src/Microsoft.DotNet.CodeFormatting/Rules/CopyrightHeaderRule.cs

@@ -79,6 +79,7 @@ private List<string> GetExistingHeader(SyntaxTriviaList triviaList)
                 {
                     headerList.Add(GetCommentText(triviaList[i].ToFullString()));
                     i++;
+                    MoveToNextLineOrTrivia(triviaList, ref i);
                 }
 
                 return headerList;
@@ -113,7 +114,25 @@ private SyntaxTriviaList RemoveExistingHeader(SyntaxTriviaList oldList)
 
             private void MovePastBlankLines(SyntaxTriviaList list, ref int index)
             {
-                while (index < list.Count && IsWhiteSpaceOrNewLine(list[index]))
+                while (index < list.Count && (IsWhitespace(list[index]) || IsNewLine(list[index])))
+                {
+                    index++;
+                }
+            }
+            
+            private void MoveToNextLineOrTrivia(SyntaxTriviaList list, ref int index)
+            {
+                MovePastWhitespaces(list, ref index);
+
+                if (index < list.Count && IsNewLine(list[index]))
+                {
+                    index++;
+                }
+            }
+
+            private void MovePastWhitespaces(SyntaxTriviaList list, ref int index)
+            {
+                while (index < list.Count && IsWhitespace(list[index]))
                 {
                     index++;
                 }
@@ -123,7 +142,8 @@ private void MovePastBlankLines(SyntaxTriviaList list, ref int index)
 
             protected abstract bool IsLineComment(SyntaxTrivia trivia);
 
-            protected abstract bool IsWhiteSpaceOrNewLine(SyntaxTrivia trivia);
+            protected abstract bool IsWhitespace(SyntaxTrivia trivia);
+            protected abstract bool IsNewLine(SyntaxTrivia trivia);
 
             protected abstract SyntaxTrivia CreateLineComment(string commentText);