1--TEST--
2Check that SplDoublyLinkedList::add generate a warning and returns a NULL with a missing value argument
3--FILE--
4<?php
5$dll = new SplDoublyLinkedList();
6var_dump($dll->add(2));
7?>
8--EXPECTF--
9Warning: SplDoublyLinkedList::add() expects exactly 2 parameters, 1 given in %s on line %d
10NULL
11