Fix SA1509 getting reported for consecutive blocks

Fixes #689

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1509UnitTests.cs

@@ -637,6 +637,42 @@ void Bar()
             await this.VerifyCSharpDiagnosticAsync(testCode, EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
         }
 
+        [Fact]
+        public async Task TestBlockStatementsAsync()
+        {
+            var testCode = @"
+class Foo
+{
+    void Bar()
+    {
+
+        {
+        }
+
+        {
+        }
+    }
+}";
+
+            var fixedCode = @"
+class Foo
+{
+    void Bar()
+    {
+        {
+        }
+
+        {
+        }
+    }
+}";
+
+            DiagnosticResult expected = this.CSharpDiagnostic().WithLocation(7, 9);
+            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 TestComplex1Async()
         {

StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1509OpeningBracesMustNotBePrecededByBlankLine.cs

@@ -8,6 +8,7 @@ namespace StyleCop.Analyzers.LayoutRules
     using System.Linq;
     using Microsoft.CodeAnalysis;
     using Microsoft.CodeAnalysis.CSharp;
+    using Microsoft.CodeAnalysis.CSharp.Syntax;
     using Microsoft.CodeAnalysis.Diagnostics;
     using StyleCop.Analyzers.Helpers;
 
@@ -79,6 +80,18 @@ private static void HandleSyntaxTree(SyntaxTreeAnalysisContext context)
 
             foreach (var openBrace in openBraces)
             {
+                BlockSyntax blockSyntax = openBrace.Parent as BlockSyntax;
+                if (blockSyntax != null)
+                {
+                    BlockSyntax parentBlock = blockSyntax.Parent as BlockSyntax;
+                    if (parentBlock != null && parentBlock.Statements[0] != blockSyntax)
+                    {
+                        // Do not disallow a blank line before an independent block, unless it is the first child of its
+                        // parent.
+                        continue;
+                    }
+                }
+
                 AnalyzeOpenBrace(context, openBrace);
             }
         }