For option , we can create a list of coupons that are valid as of a certain date, then pass in that date. 윤년에는 어떻게 되는지 등 모든 종류의 흥미로운 시나리오를 테스트할 수 있습니다. We can provide a different response if the couponid was invalid than if the couponid was just expired.