--TEST-- MongoDB\BSON\Undefined serialization --FILE-- <?php var_dump($undefined = MongoDB\BSON\toPHP(MongoDB\BSON\fromJSON('{ "undefined": {"$undefined": true} }'))->undefined); var_dump($s = serialize($undefined)); var_dump(unserialize($s)); ?> ===DONE=== <?php exit(0); ?> --EXPECTF-- object(MongoDB\BSON\Undefined)#%d (%d) { } string(34) "C:22:"MongoDB\BSON\Undefined":0:{}" object(MongoDB\BSON\Undefined)#%d (%d) { } ===DONE===