def test_rightRotationOnRoot(self):
     tree = AVLTree()
     tree.insert(3)
     tree.insert(2)
     tree.insert(1)
     tree.root = tree.right_rotation(tree.root)
     nodes = tree.preorder_traversal()
     self.assertEqual(nodes, [2, 1, 3])
 def test_rightRotationNoRoot(self):
     tree = AVLTree()
     tree.right_rotation(tree.root)
     nodes = tree.preorder_traversal()
     self.assertEqual(nodes, [])