public void MaxDepthTest()
{
BinarySearchTree<int> bst = ConstructTree(5, 4, 8);
Assert.AreEqual(2, bst.MaxDepth(bst.RootNode));
bst = ConstructTree(5);
Assert.AreEqual(1, bst.MaxDepth(bst.RootNode));
bst = new BinarySearchTree<int>();
Assert.AreEqual(0, bst.MaxDepth(bst.RootNode));
}