Update SA1516 to handle assembly attributes

Fixes #1923

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/LayoutRules/SA1516CodeFixProvider.cs

@@ -142,6 +142,11 @@ private static SyntaxNode GetRelevantNode(SyntaxNode innerNode)
                     return currentNode;
                 }
 
+                if (currentNode is AttributeListSyntax)
+                {
+                    return currentNode;
+                }
+
                 currentNode = currentNode.Parent;
             }
 

StyleCop.Analyzers/StyleCop.Analyzers.Test/LayoutRules/SA1516UnitTests.cs

@@ -713,5 +713,33 @@ private set
 
             await VerifyCSharpFixAsync(testCode, expected, fixedTestCode, CancellationToken.None).ConfigureAwait(false);
         }
+
+        [Theory]
+        [InlineData("namespace")]
+        [InlineData("public class")]
+        [WorkItem(1923, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/1923")]
+        public async Task TestBlankLinesAroundAssemblyAttributesAsync(string followingElementKind)
+        {
+            string testCode = $@"using System.Runtime.CompilerServices;
+[assembly: InternalsVisibleTo(""AnotherAssembly"")]
+{followingElementKind} Foo
+{{
+}}";
+            string fixedTestCode = $@"using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo(""AnotherAssembly"")]
+
+{followingElementKind} Foo
+{{
+}}";
+
+            var expected = new[]
+            {
+                Diagnostic().WithLocation(2, 1),
+                Diagnostic().WithLocation(3, 1),
+            };
+
+            await VerifyCSharpFixAsync(testCode, expected, fixedTestCode, CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }

StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1516ElementsMustBeSeparatedByBlankLine.cs

@@ -169,20 +169,43 @@ private static void HandleCompilationUnit(SyntaxNodeAnalysisContext context, Sty
         {
             var compilationUnit = (CompilationUnitSyntax)context.Node;
 
+            var externs = compilationUnit.Externs;
             var usings = compilationUnit.Usings;
+            var attributeLists = compilationUnit.AttributeLists;
             var members = compilationUnit.Members;
 
             HandleUsings(context, usings, settings);
             HandleMemberList(context, members);
 
-            if (members.Count > 0 && compilationUnit.Usings.Count > 0)
+            SyntaxNode previousItem = externs.LastOrDefault();
+            if (usings.Any())
             {
-                ReportIfThereIsNoBlankLine(context, usings[usings.Count - 1], members[0]);
+                if (previousItem != null)
+                {
+                    ReportIfThereIsNoBlankLine(context, previousItem, usings[0]);
+                }
+
+                previousItem = usings.Last();
             }
 
-            if (compilationUnit.Usings.Count > 0 && compilationUnit.Externs.Count > 0)
+            if (attributeLists.Any())
             {
-                ReportIfThereIsNoBlankLine(context, compilationUnit.Externs[compilationUnit.Externs.Count - 1], compilationUnit.Usings[0]);
+                if (previousItem != null)
+                {
+                    ReportIfThereIsNoBlankLine(context, previousItem, attributeLists[0]);
+                }
+
+                previousItem = attributeLists.Last();
+            }
+
+            if (members.Any())
+            {
+                if (previousItem != null)
+                {
+                    ReportIfThereIsNoBlankLine(context, previousItem, members[0]);
+                }
+
+                previousItem = members.Last();
             }
         }