public void TreeViewItemsSourceUpdateTest() { var treeView = new TreeView(); var items = CreateTreeViewItemsSource(); treeView.ItemsSource = items; // Insert var newItem = new TreeViewItemSource() { Content = "newItem" }; items.Add(newItem); Verify.AreEqual(treeView.RootNodes.Count, 3); var itemFromNode = treeView.RootNodes[2].Content as TreeViewItemSource; Verify.AreEqual(newItem.Content, itemFromNode.Content); // Remove items.Remove(newItem); Verify.AreEqual(treeView.RootNodes.Count, 2); // Replace var item3 = new TreeViewItemSource() { Content = "3" }; items[1] = item3; itemFromNode = treeView.RootNodes[1].Content as TreeViewItemSource; Verify.AreEqual(item3.Content, itemFromNode.Content); // Clear items.Clear(); Verify.AreEqual(treeView.RootNodes.Count, 0); }