Correct default public interface extraction

Author: IvenBach

Rubberduck.Core/UI/Refactorings/ExtractInterface/ExtractInterfaceViewModel.cs

@@ -7,7 +7,6 @@
 using Rubberduck.Parsing.Symbols;
 using Rubberduck.Refactorings.ExtractInterface;
 using Rubberduck.UI.Command;
-using System.Windows.Data;
 
 namespace Rubberduck.UI.Refactorings
 {
@@ -70,8 +69,6 @@ public bool IsPrivateInterfaceEnabled
             }
         }
 
-        private readonly IValueConverter classInstancingConverter = new Converters.ClassInstancingToBooleanConverter();
-
         private bool isPublicInterfaceChecked = true;
         public bool IsPublicInterfaceChecked
         {
@@ -83,7 +80,9 @@ public bool IsPublicInterfaceChecked
                     return;
                 }
 
-                Model.ImplementingClassInstancing = (ClassInstancing)classInstancingConverter.ConvertBack(value, null, null, null);
+                Model.InterfaceInstancing = value 
+                    ? ClassInstancing.PublicNotCreatable 
+                    : ClassInstancing.Private;
                 isPublicInterfaceChecked = value;
                 OnPropertyChanged();                
             }

Rubberduck.Refactorings/ExtractInterface/ExtractInterfaceModel.cs

@@ -20,7 +20,10 @@ public class ExtractInterfaceModel : IRefactoringModel
         public string InterfaceName { get; set; }
         public ObservableCollection<InterfaceMember> Members { get; set; } = new ObservableCollection<InterfaceMember>();
         public IEnumerable<InterfaceMember> SelectedMembers => Members.Where(m => m.IsSelected);
-        public ClassInstancing ImplementingClassInstancing { get; set; }
+        public ClassInstancing ImplementingClassInstancing => System.Convert.ToBoolean(TargetDeclaration.Attributes.ExposedAttribute.Values.First())
+                ? ClassInstancing.PublicNotCreatable
+                : ClassInstancing.Private;
+        public ClassInstancing InterfaceInstancing { get; set; } = ClassInstancing.PublicNotCreatable;
 
         public static readonly DeclarationType[] MemberTypes =
         {
@@ -35,9 +38,6 @@ public ExtractInterfaceModel(IDeclarationFinderProvider declarationFinderProvide
         {
             TargetDeclaration = target;
             DeclarationFinderProvider = declarationFinderProvider;
-            ImplementingClassInstancing = System.Convert.ToBoolean(target.Attributes.ExposedAttribute.Values.First())
-                ? ClassInstancing.PublicNotCreatable
-                : ClassInstancing.Private;
 
             if (TargetDeclaration == null)
             {

Rubberduck.Refactorings/ExtractInterface/ExtractInterfaceRefactoring.cs

@@ -98,7 +98,7 @@ private void AddInterface(ExtractInterfaceModel model)
                 return; //The target project is not available.
             }
 
-            AddInterfaceClass(model.TargetDeclaration, model.InterfaceName, GetInterfaceModuleBody(model), model.ImplementingClassInstancing);
+            AddInterfaceClass(model.TargetDeclaration, model.InterfaceName, GetInterfaceModuleBody(model), model.InterfaceInstancing);
 
             var rewriteSession = RewritingManager.CheckOutCodePaneSession();
             var rewriter = rewriteSession.CheckOutModuleRewriter(model.TargetDeclaration.QualifiedModuleName);