def test_add_to_back_to_empty_list(capsys):
    linked_list = LinkedList()
    node_to_add = LinkedListNode(1)
    node_2 = LinkedListNode(2)
    node_to_add.next = node_2

    linked_list.add_to_back(node_to_add)
    linked_list.print()

    expected = "1 -> 2 -> NULL\n"
    output = capsys.readouterr().out
    assert output == expected
def test_add_to_back_one_element(capsys):
    node_1 = LinkedListNode(1)
    node_2 = LinkedListNode(2)
    node_3 = LinkedListNode(3)
    linked_list = LinkedList(node_1)
    linked_list.head.next = node_2

    linked_list.add_to_back(node_3)
    linked_list.print()

    expected = "1 -> 2 -> 3 -> NULL\n"
    output = capsys.readouterr().out
    assert output == expected