1--TEST-- 2Check that SplDoublyLinkedList::add generate a warning and returns a NULL with missing arguments 3--FILE-- 4<?php 5$dll = new SplDoublyLinkedList(); 6var_dump($dll->add()); 7?> 8--EXPECTF-- 9Warning: SplDoublyLinkedList::add() expects exactly 2 parameters, 0 given in %s on line %d 10NULL 11