add test should_return_promotion_list_when_input_barcode
add getPromotionTypeList method
modify buildProduct method
modify test should_return_a_product_list
add PromotionHelperTest
add test should_return_12_when_input_cartItem
add calculatMoney
add getPromotion method
refactor promotionHelper
add Pos
add fields and methods
modify calculateMoney
add printInventory
add getDate method
buildCartItemString
buildTotalMoneyString
formate pos.java