fix: #5: system types cannot be included as mixins

All types that are stored in CLR module cannot be included as mixins

MixinRefactoring.Test/Integration/Dummys/Person.cs

@@ -283,4 +283,18 @@ public class PersonFromAbstractName : PersonWithAbstractName
     {
         private SimpleName _name;
     }
+
+    /// <summary>
+    /// this class has only native data types
+    /// and therefore no mixins should be implemented
+    /// </summary>
+    public class PersonWithNativeTypes
+    {
+        private int _int;
+        private string _string;
+        private byte _byte;
+        private double _double;
+        private decimal _decimal;
+        private IEnumerable<int> _enumerable;
+    }
 }

MixinRefactoring.Test/Integration/IncludeMixinSyntaxWriterTest.cs

@@ -4,7 +4,6 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.CSharp;
-using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 
 namespace MixinRefactoring.Test
 {

MixinRefactoring.Test/Integration/MixinCommandTest.cs

@@ -0,0 +1,31 @@
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+
+namespace MixinRefactoring.Test
+{
+    [TestFixture]
+    public class MixinCommandTest
+    {
+        [Test]
+        public void ClassWithNativeFields_CanExecuteMixinCommand_CannotExecute()
+        {
+            // arrange
+            // 1. load source files and get class and mixin declarations
+            var sourceCode = new SourceCode("Person.cs");
+            var personClass = sourceCode.Class("PersonWithNativeTypes");
+            var fieldDeclarations = personClass.DescendantNodes().OfType<FieldDeclarationSyntax>();
+
+            foreach(var fieldDeclaration in fieldDeclarations)
+            {
+                var mixinCommand = new MixinCommand(sourceCode.Semantic, fieldDeclaration);
+                Assert.IsFalse(mixinCommand.CanExecute());
+            }
+        }
+    }
+}

MixinRefactoring.Test/MixinRefactoring.Test.csproj

@@ -119,6 +119,7 @@
     <Compile Include="Integration\MethodSyntaxReaderTest.cs" />
     <Compile Include="Integration\ParameterSyntaxReaderTest.cs" />
     <Compile Include="Integration\PropertySyntaxReaderTest.cs" />
+    <Compile Include="Integration\MixinCommandTest.cs" />
     <Compile Include="Unit\SemanticTypeReaderTest.cs" />
     <Compile Include="Unit\MemberCompareTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

MixinRefactoring.Vsix/source.extension.vsixmanifest

@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <PackageManifest Version="2.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2011" xmlns:d="http://schemas.microsoft.com/developer/vsx-schema-design/2011">
   <Metadata>
-    <Identity Id="mixinSharp..6af25ee5-c001-4b3b-85f4-e7785ff466f0" Version="0.9.1" Language="en-US" Publisher="Patric Genfer"/>
+    <Identity Id="mixinSharp..6af25ee5-c001-4b3b-85f4-e7785ff466f0" Version="1.0.0" Language="en-US" Publisher="Patric Genfer"/>
     <DisplayName>mixinSharp</DisplayName>
     <Description xml:space="preserve">A code refactoring extension that adds mixin support to C# by auto generating the required code.</Description>
+    <MoreInfo>https://github.com/pgenfer/mixinSharp/wiki</MoreInfo>
     <License>license.txt</License>
     <GettingStartedGuide>https://github.com/pgenfer/mixinSharp/wiki/Tutorial</GettingStartedGuide>
     <Icon>mixin_logo.png</Icon>

MixinRefactoring/SyntaxReader/FieldSyntaxReader.cs

@@ -10,6 +10,12 @@ namespace MixinRefactoring
 {
     public class FieldSyntaxReader : SyntaxWalkerWithSemantic
     {
+        /// <summary>
+        /// string constant used to identify the CLR module by name
+        /// (the place where the system types are defined)
+        /// </summary>
+        private const string CommonLanguageRuntimeLibrary = "CommonLanguageRuntimeLibrary";
+
         public MixinReference MixinReference { get; private set; }
 
         public FieldSyntaxReader(SemanticModel semantic):base(semantic)
@@ -28,6 +34,13 @@ public override void VisitVariableDeclarator(VariableDeclaratorSyntax node)
             // type could not be resolved => return here
             if (typeOfField.TypeKind == TypeKind.Error)
                 return;
+
+            // also ignore native types (like int, string, double etc...)
+            // we identify them by checking if the types are declared in the runtime itself
+            // if yes, they are system types and we will skip them
+            var module = typeOfField.ContainingModule;
+            if (module != null && module.Name == CommonLanguageRuntimeLibrary)
+                return;          
 
             var classFactory = new ClassFactory(_semantic);
             // create the mixin reference, that is the name of the field and the type the field references