def test_postOrder():
t = BinaryTreeSearch()
t.add(5)
t.add(9)
t.add(4)
t.add(14)
t.add(7)
t.add(6)
t.add(3)
actual = t.postOrder()
expected = [
3,
4,
6,
7,
14,
9,
5,
]
assert actual == expected
def test_postOrder_on_empty():
t = BinaryTreeSearch()
actual = t.postOrder()
expected = [None]
assert actual == expected