Update SA1400 to recognize modifier "file"

#3588

Author: bjornhellander

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp11/MaintainabilityRules/SA1400CSharp11UnitTests.cs

@@ -3,9 +3,26 @@
 
 namespace StyleCop.Analyzers.Test.CSharp11.MaintainabilityRules
 {
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Microsoft.CodeAnalysis.Testing;
     using StyleCop.Analyzers.Test.CSharp10.MaintainabilityRules;
+    using StyleCop.Analyzers.Test.Helpers;
+    using Xunit;
+    using static StyleCop.Analyzers.Test.Verifiers.StyleCopCodeFixVerifier<
+        StyleCop.Analyzers.MaintainabilityRules.SA1400AccessModifierMustBeDeclared,
+        StyleCop.Analyzers.MaintainabilityRules.SA1400CodeFixProvider>;
 
     public class SA1400CSharp11UnitTests : SA1400CSharp10UnitTests
     {
+        [Theory]
+        [MemberData(nameof(CommonMemberData.BaseTypeDeclarationKeywords), MemberType = typeof(CommonMemberData))]
+        [WorkItem(3588, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/3588")]
+        public async Task TestTypeDeclarationWithFileModifierAsync(string typeName)
+        {
+            var testCode = $@"file {typeName} TypeName {{ }}";
+
+            await VerifyCSharpDiagnosticAsync(testCode, DiagnosticResult.EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp11/StyleCop.Analyzers.Test.CSharp11.csproj

@@ -17,7 +17,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.2.0-4.final" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.4.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" PrivateAssets="all" />
   </ItemGroup>

StyleCop.Analyzers/StyleCop.Analyzers/Lightup/SyntaxKindEx.cs

@@ -14,6 +14,7 @@ internal static class SyntaxKindEx
         public const SyntaxKind NotKeyword = (SyntaxKind)8440;
         public const SyntaxKind ManagedKeyword = (SyntaxKind)8445;
         public const SyntaxKind UnmanagedKeyword = (SyntaxKind)8446;
+        public const SyntaxKind FileKeyword = (SyntaxKind)8449;
         public const SyntaxKind NullableKeyword = (SyntaxKind)8486;
         public const SyntaxKind EnableKeyword = (SyntaxKind)8487;
         public const SyntaxKind WarningsKeyword = (SyntaxKind)8488;

StyleCop.Analyzers/StyleCop.Analyzers/MaintainabilityRules/SA1400AccessModifierMustBeDeclared.cs

@@ -13,6 +13,7 @@ namespace StyleCop.Analyzers.MaintainabilityRules
     using Microsoft.CodeAnalysis.CSharp.Syntax;
     using Microsoft.CodeAnalysis.Diagnostics;
     using StyleCop.Analyzers.Helpers;
+    using StyleCop.Analyzers.Lightup;
 
     /// <summary>
     /// The access modifier for a C# element has not been explicitly defined.
@@ -189,6 +190,7 @@ private static void CheckAccessModifiers(SyntaxNodeAnalysisContext context, Synt
                 case SyntaxKind.ProtectedKeyword:
                 case SyntaxKind.InternalKeyword:
                 case SyntaxKind.PrivateKeyword:
+                case SyntaxKindEx.FileKeyword:
                     return;
 
                 case SyntaxKind.StaticKeyword: