--TEST--
Test date_interval_create_from_date_string() function : null parameter 
--CREDITS--
Rodrigo Prado de Jesus <royopa [at] gmail [dot] com>
--FILE--
<?php
$i = date_interval_create_from_date_string(null); //returns a empty object
var_dump($i);
?>
--EXPECTF--
object(DateInterval)#1 (15) {
  ["y"]=>
  int(0)
  ["m"]=>
  int(0)
  ["d"]=>
  int(0)
  ["h"]=>
  int(0)
  ["i"]=>
  int(0)
  ["s"]=>
  int(0)
  ["weekday"]=>
  int(0)
  ["weekday_behavior"]=>
  int(0)
  ["first_last_day_of"]=>
  int(0)
  ["invert"]=>
  int(0)
  ["days"]=>
  int(0)
  ["special_type"]=>
  int(0)
  ["special_amount"]=>
  int(0)
  ["have_weekday_relative"]=>
  int(0)
  ["have_special_relative"]=>
  int(0)
}