protected void AddChildren(Item item)
 {
     for (int i = 0; i < 10; i++)
     {
         var childItem = new Item(string.Format("ChildItem {0}", i));
         item.Children.Add(childItem);
     }
 }
 protected Item BuildTestItem()
 {
     var item = new Item("ParentItem");
     AddChildren(item);
     return item;
 }
        protected override void Arrange()
        {
            base.Arrange();
            item = BuildTestItem();

        }