public function diffWorks()
{
$earlierTime = \DateTime::createFromFormat('Y-m-d H:i:s', '2013-07-03 12:34:56');
$futureTime = \DateTime::createFromFormat('Y-m-d H:i:s', '2013-07-10 12:33:56');
$helper = new DateHelper();
$result = $helper->diff($earlierTime, $futureTime);
$this->assertEquals(6, $result->d);
$this->assertEquals(23, $result->h);
$this->assertEquals(59, $result->i);
}