public function testIntervalAndStartAt()
{
$expireAt = new \DateTime('2014-01-15');
$number = 3;
$unit = ReminderInterval::UNIT_DAY;
$interval = new ReminderInterval($number, $unit);
$this->assertNull($this->entity->getStartAt());
$this->entity->setExpireAt($expireAt);
$this->entity->setInterval($interval);
$this->assertAttributeEquals($number, 'intervalNumber', $this->entity);
$this->assertAttributeEquals($unit, 'intervalUnit', $this->entity);
$this->assertEquals(new \DateTime('2014-01-12'), $this->entity->getStartAt());
}