public function testMonthOffsetReturnsExpectedDates()
{
$this->object->setFirstDate(\DateTime::createFromFormat('Y-m-d', '2014-01-01'));
$this->object->setLastDate(\DateTime::createFromFormat('Y-m-d', '2014-03-01'));
$this->object->setOpt('interval', 'P1M');
$range = $this->object->getRange();
$this->assertEquals('2014-01-01', $range['2014-01-01']['formatted']);
$this->assertEquals('2014-02-01', $range['2014-02-01']['formatted']);
$this->assertEquals('2014-03-01', $range['2014-03-01']['formatted']);
}