Make DataTemplate-created TreeViewItems namescopes.

Closes #463.

src/Perspex.Controls/Generators/TreeItemContainerGenerator.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using Perspex.Controls.Templates;
 
@@ -84,6 +83,7 @@ namespace Perspex.Controls.Generators
                     result.DataContext = item;
                 }
 
+                NameScope.SetNameScope((Control)(object)result, new NameScope());
                 Index.Add(item, result);
 
                 return result;

tests/Perspex.Controls.UnitTests/TreeViewTests.cs

@@ -210,6 +210,48 @@ namespace Perspex.Controls.UnitTests
                 dataContexts);
         }
 
+        [Fact]
+        public void Control_Item_Should_Not_Be_NameScope()
+        {
+            var items = new object[]
+            {
+                new TreeViewItem(),
+            };
+
+            var target = new TreeView
+            {
+                Template = CreateTreeViewTemplate(),
+                Items = items,
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var item = target.Presenter.Panel.LogicalChildren[0];
+            Assert.Null(NameScope.GetNameScope((TreeViewItem)item));
+        }
+
+        [Fact]
+        public void DataTemplate_Created_Item_Should_Be_NameScope()
+        {
+            var items = new object[]
+            {
+                "foo",
+            };
+
+            var target = new TreeView
+            {
+                Template = CreateTreeViewTemplate(),
+                Items = items,
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var item = target.Presenter.Panel.LogicalChildren[0];
+            Assert.NotNull(NameScope.GetNameScope((TreeViewItem)item));
+        }
+
         private void ApplyTemplates(TreeView tree)
         {
             tree.ApplyTemplate();