Add initial tests for AccessorDeclarationSyntaxExtensions

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp7/Lightup/AccessorDeclarationSyntaxExtensionsTests.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+namespace StyleCop.Analyzers.Test.CSharp7.Lightup
+{
+    using Microsoft.CodeAnalysis.CSharp;
+    using StyleCop.Analyzers.Lightup;
+    using Xunit;
+
+    public class AccessorDeclarationSyntaxExtensionsTests
+    {
+        [Fact]
+        public void TestExpressionBody()
+        {
+            var accessorDeclarationSyntax = SyntaxFactory.AccessorDeclaration(SyntaxKind.GetAccessorDeclaration)
+                .WithExpressionBody(SyntaxFactory.ArrowExpressionClause(SyntaxFactory.LiteralExpression(SyntaxKind.NullLiteralExpression)));
+            Assert.Same(accessorDeclarationSyntax.ExpressionBody, AccessorDeclarationSyntaxExtensions.ExpressionBody(accessorDeclarationSyntax));
+        }
+
+        [Fact]
+        public void TestWithExpressionBody()
+        {
+            var accessorDeclarationSyntax = SyntaxFactory.AccessorDeclaration(SyntaxKind.GetAccessorDeclaration);
+            var expressionBody = SyntaxFactory.ArrowExpressionClause(SyntaxFactory.LiteralExpression(SyntaxKind.NullLiteralExpression));
+            var accessorWithBody = AccessorDeclarationSyntaxExtensions.WithExpressionBody(accessorDeclarationSyntax, expressionBody);
+            Assert.Null(accessorDeclarationSyntax.ExpressionBody);
+            Assert.NotNull(accessorWithBody.ExpressionBody);
+            Assert.Equal(SyntaxKind.NullLiteralExpression, accessorWithBody.ExpressionBody.Expression.Kind());
+        }
+    }
+}

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp7/StyleCop.Analyzers.Test.CSharp7.csproj

@@ -194,6 +194,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Lightup\AccessorDeclarationSyntaxExtensionsTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>

StyleCop.Analyzers/StyleCop.Analyzers.Test/Lightup/AccessorDeclarationSyntaxExtensionsTests.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+namespace StyleCop.Analyzers.Test.Lightup
+{
+    using System;
+    using Microsoft.CodeAnalysis.CSharp;
+    using StyleCop.Analyzers.Lightup;
+    using Xunit;
+
+    public class AccessorDeclarationSyntaxExtensionsTests
+    {
+        [Fact]
+        public void TestExpressionBody()
+        {
+            var accessorDeclarationSyntax = SyntaxFactory.AccessorDeclaration(SyntaxKind.GetAccessorDeclaration);
+            Assert.Null(AccessorDeclarationSyntaxExtensions.ExpressionBody(accessorDeclarationSyntax));
+        }
+
+        [Fact]
+        public void TestWithExpressionBody()
+        {
+            var accessorDeclarationSyntax = SyntaxFactory.AccessorDeclaration(SyntaxKind.GetAccessorDeclaration);
+
+            // With default value is allowed
+            var accessorWithDefaultBody = AccessorDeclarationSyntaxExtensions.WithExpressionBody(accessorDeclarationSyntax, null);
+            Assert.Null(AccessorDeclarationSyntaxExtensions.ExpressionBody(accessorWithDefaultBody));
+
+            // Non-default throws an exception
+            var expressionBody = SyntaxFactory.ArrowExpressionClause(SyntaxFactory.LiteralExpression(SyntaxKind.NullLiteralExpression));
+            Assert.Throws<NotSupportedException>(() => AccessorDeclarationSyntaxExtensions.WithExpressionBody(accessorDeclarationSyntax, expressionBody));
+        }
+    }
+}

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

@@ -235,6 +235,7 @@
     <Compile Include="LayoutRules\SA1518UnitTests.cs" />
     <Compile Include="LayoutRules\SA1519UnitTests.cs" />
     <Compile Include="LayoutRules\SA1520UnitTests.cs" />
+    <Compile Include="Lightup\AccessorDeclarationSyntaxExtensionsTests.cs" />
     <Compile Include="LinqHelpers\SyntaxTriviaListEnumerableTests.cs" />
     <Compile Include="MaintainabilityRules\DebugMessagesUnitTestsBase.cs" />
     <Compile Include="MaintainabilityRules\FileMayOnlyContainTestBase.cs" />

StyleCop.Analyzers/StyleCop.Analyzers/Lightup/AccessorDeclarationSyntaxExtensions.cs

@@ -4,9 +4,6 @@
 namespace StyleCop.Analyzers.Lightup
 {
     using System;
-    using System.Linq;
-    using System.Linq.Expressions;
-    using System.Reflection;
     using Microsoft.CodeAnalysis.CSharp.Syntax;
 
     internal static class AccessorDeclarationSyntaxExtensions
@@ -16,40 +13,8 @@ internal static class AccessorDeclarationSyntaxExtensions
 
         static AccessorDeclarationSyntaxExtensions()
         {
-            if (LightupHelpers.SupportsCSharp7)
-            {
-                {
-                    var expressionBodyProperty = typeof(AccessorDeclarationSyntax).GetTypeInfo().GetDeclaredProperty(nameof(ExpressionBody));
-                    var syntaxParameter = Expression.Parameter(typeof(AccessorDeclarationSyntax), "syntax");
-                    Expression<Func<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax>> expression =
-                        Expression.Lambda<Func<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax>>(
-                            Expression.Call(syntaxParameter, expressionBodyProperty.GetMethod),
-                            syntaxParameter);
-                    ExpressionBodyAccessor = expression.Compile();
-                }
-
-                {
-                    var withExpressionBodyMethod = typeof(AccessorDeclarationSyntax).GetTypeInfo().GetDeclaredMethods(nameof(WithExpressionBody))
-                        .Single(method => method.GetParameters().Length == 1 && method.GetParameters()[0].ParameterType == typeof(ArrowExpressionClauseSyntax));
-                    var syntaxParameter = Expression.Parameter(typeof(AccessorDeclarationSyntax), "syntax");
-                    var expressionBodyParameter = Expression.Parameter(typeof(ArrowExpressionClauseSyntax), "expressionBody");
-                    Expression<Func<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax, AccessorDeclarationSyntax>> expression =
-                        Expression.Lambda<Func<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax, AccessorDeclarationSyntax>>(
-                            Expression.Call(syntaxParameter, withExpressionBodyMethod, expressionBodyParameter),
-                            syntaxParameter,
-                            expressionBodyParameter);
-                    WithExpressionBodyAccessor = expression.Compile();
-                }
-            }
-            else
-            {
-                ExpressionBodyAccessor = syntax => null;
-                WithExpressionBodyAccessor =
-                    (syntax, expressionBody) =>
-                    {
-                        throw new NotSupportedException("Expression-bodied accessors are only available in C# 7+.");
-                    };
-            }
+            ExpressionBodyAccessor = LightupHelpers.CreateSyntaxPropertyAccessor<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax>(typeof(AccessorDeclarationSyntax), nameof(ExpressionBody));
+            WithExpressionBodyAccessor = LightupHelpers.CreateSyntaxWithPropertyAccessor<AccessorDeclarationSyntax, ArrowExpressionClauseSyntax>(typeof(AccessorDeclarationSyntax), nameof(ExpressionBody));
         }
 
         public static ArrowExpressionClauseSyntax ExpressionBody(this AccessorDeclarationSyntax syntax)

StyleCop.Analyzers/StyleCop.Analyzers/Lightup/LightupHelpers.cs

@@ -123,7 +123,7 @@ internal static Func<TSyntax, TProperty, TSyntax> CreateSyntaxWithPropertyAccess
             }
 
             var methodInfo = type.GetTypeInfo().GetDeclaredMethods("With" + propertyName)
-                .Single(m => !m.IsStatic && m.GetParameters().Length == 1 && m.GetParameters()[0].GetType().Equals(property.PropertyType));
+                .Single(m => !m.IsStatic && m.GetParameters().Length == 1 && m.GetParameters()[0].ParameterType.Equals(property.PropertyType));
 
             var syntaxParameter = Expression.Parameter(typeof(TSyntax), "syntax");
             var valueParameter = Expression.Parameter(typeof(TProperty), methodInfo.GetParameters()[0].Name);