def test_double_rotation_with_left_zig_zag_tree(self):
node_12 = create_zig_zag_tree_left_right()
tree = AVL(node_12)
returned_node = tree._double_rotation(node_12)
node_8 = tree.get_root()
node_6 = node_8.get_left_child()
node_12 = node_8.get_right_child()
expect(node_8.get_key()).to.be.equal(8)
expect(node_6.get_key()).to.be.equal(6)
expect(node_12.get_key()).to.be.equal(12)
expect(returned_node).to.be.equal(node_8)
