public function testGetHour()
 {
     $calendar = new Calendar();
     $hour = $calendar->getHour(new \DateTime('2012-01-01 17:00'));
     $this->assertInstanceOf('CalendR\\Period\\Hour', $hour);
     $hour = $calendar->getHour(2012, 1, 1, 17);
     $this->assertInstanceOf('CalendR\\Period\\Hour', $hour);
 }