public function providerInvalidDates()
{
return array(array('', 'Y-m-d'), array(false, 'Y-m-d'), array(null, 'Y-m-d'), array(new stdClass(), 'Y-m-d'), array('2015-13-01', 'Y-m-d'), array('2015-01-32', 'Y-m-d'), array('2015-01', 'Y-m-d'), array('2015-01-01', 'd-m-Y'));
}