def test_postorder_traversal(nodes, expected):
root = bst.create(nodes)
index = 0
for node in bst.postorder(root):
assert node.val == expected[index]
index += 1
def test_bst_create(nodes, expected):
root = bst.create(nodes)
assert root.val == expected
def test_search_iter_fail(nodes, nonexistent):
root = bst.create(nodes)
assert bst.search_iter(root, nonexistent) is None
def test_maximum(nodes, expected):
root = bst.create(nodes)
result = bst.maximum(root)
assert result.val == expected
def test_search_iter(nodes, target):
root = bst.create(nodes)
result = bst.search_iter(root, target)
assert result.val == target
