/** * @dataProvider arraySet1 */ public function testWalk($array) { // callback function used for mapping $callable = function ($item) { if (is_array($item)) { $item['new'] = 'value'; } else { $item = $item . '_appended'; } return $item; }; $a = new ArrayObject($array); $a->walk($callable); array_walk($array, $callable); $this->assertSame($array, $a->val()); }