modify import
mock ItemImple class
add getter of ItemImple
mock itemImple of ItemService
create BuyTwoOneFreePromotionTest class
add BuyTwoOneFreePromotion subclass
set Promotion to father class
finish calculatePromotion of BuyTwoOneFreePromotion
modify object of Promotion
create SecondHalfPromotionTest
create SecondHalfPromotion class
finish SecondHalfPromotionTest
create DiscountPromotionTest class
new DiscountPromotion class
finish DiscountPromotionTest
add CategoryFactoryTest class
modify constructor
new PromotionFactory class
modify constructor
finish test of PromotionFactory