Put extracted interfaces in same folder as the origin

Author: MDoerner

Rubberduck.Refactorings/ExtractInterface/ExtractInterfaceRefactoringAction.cs

@@ -74,10 +74,17 @@ private static string InterfaceModuleBody(ExtractInterfaceModel model)
         {
             var interfaceMembers = string.Join(Environment.NewLine, model.SelectedMembers.Select(m => m.Body));
             var optionExplicit = $"{Tokens.Option} {Tokens.Explicit}{Environment.NewLine}";
+
+            var targetModule = Declaration.GetModuleParent(model.TargetDeclaration);
+            var folderAnnotation = targetModule?.Annotations.FirstOrDefault(pta => pta.Annotation is FolderAnnotation);
+            var folderAnnotationText = folderAnnotation != null
+                                       ? $"'@{folderAnnotation.Context.GetText()}{Environment.NewLine}"
+                                       : string.Empty;
+
             var interfaceAnnotation = new InterfaceAnnotation();
             var interfaceAnnotationText = $"'@{interfaceAnnotation.Name}{Environment.NewLine}";
 
-            return $"{optionExplicit}{Environment.NewLine}{interfaceAnnotationText}{Environment.NewLine}{interfaceMembers}";
+            return $"{optionExplicit}{Environment.NewLine}{folderAnnotationText}{interfaceAnnotationText}{Environment.NewLine}{interfaceMembers}";
         }
 
         private void AddImplementsStatement(ExtractInterfaceModel model, IRewriteSession rewriteSession)

RubberduckTests/Refactoring/ExtractInterfaceTests.cs

@@ -652,6 +652,58 @@ End Sub
             Assert.AreEqual(expectedInterfaceCode, actualInterfaceCode);
         }
 
+        [Test]
+        [Category("Refactorings")]
+        [Category("Extract Interface")]
+        public void ExtractInterfaceRefactoring_PutsInterfaceInFolderOfClassItIsExtractedFrom()
+        {
+            //Input
+            const string inputCode =
+                @"'@Folder(""MyFolder.MySubFolder"")
+
+Public Sub Foo(ByVal arg1 As Integer, ByVal arg2 As String)
+End Sub";
+            var selection = new Selection(1, 23, 1, 27);
+
+            //Expectation
+            const string expectedCode =
+                @"Implements IClass
+
+'@Folder(""MyFolder.MySubFolder"")
+
+Public Sub Foo(ByVal arg1 As Integer, ByVal arg2 As String)
+End Sub
+
+Private Sub IClass_Foo(ByVal arg1 As Integer, ByVal arg2 As String)
+    Err.Raise 5 'TODO implement interface member
+End Sub
+";
+
+            const string expectedInterfaceCode =
+                @"Option Explicit
+
+'@Folder(""MyFolder.MySubFolder"")
+'@Interface
+
+Public Sub Foo(ByVal arg1 As Integer, ByVal arg2 As String)
+End Sub
+";
+            Func<ExtractInterfaceModel, ExtractInterfaceModel> presenterAction = model =>
+            {
+                foreach (var interfaceMember in model.Members)
+                {
+                    interfaceMember.IsSelected = true;
+                }
+
+                return model;
+            };
+
+            var actualCode = RefactoredCode("Class", selection, presenterAction, null, false, ("Class", inputCode, ComponentType.ClassModule));
+            Assert.AreEqual(expectedCode, actualCode["Class"]);
+            var actualInterfaceCode = actualCode[actualCode.Keys.Single(componentName => !componentName.Equals("Class"))];
+            Assert.AreEqual(expectedInterfaceCode, actualInterfaceCode);
+        }
+
         protected override IRefactoring TestRefactoring(IRewritingManager rewritingManager, RubberduckParserState state, IRefactoringPresenterFactory factory, ISelectionService selectionService)
         {
             var uiDispatcherMock = new Mock<IUiDispatcher>();