public void Test_Preorder_Traverse()
{
var tree = new BinaryTree<int> {90, 50, 150, 20, 75, 95, 175, 5, 25, 66, 80, 92, 111, 166, 200};
var data = new StringBuilder();
tree.Traverse(node=> data.Append(node+" "), "Preorder");
Assert.AreEqual("90 50 20 5 25 75 66 80 150 95 92 111 175 166 200 ", data.ToString());
}