public void CreateMixinFromBaseClass()
        {
            WithSourceFiles(Files.NotCompilable, Files.Mixin);
            var childClass = CreateClass("SimpleChildClassWithInterface");
            var baseInterface = childClass.SourceCode.BaseList.Types[0];

            var command = new CreateMixinFromInterfaceCommand((SimpleBaseTypeSyntax)baseInterface, Semantic);

            var result = command.Execute(childClass.SourceCode, Semantic);

            Assert.IsTrue(result.Members.Count == 2);
            Assert.IsTrue(result.Members.Any(x => x is FieldDeclarationSyntax));
            Assert.IsTrue(result.Members.Any(x => x is MemberDeclarationSyntax));
        }