add PromotionTypeTest
change abstract class to entity class
success calculate_test
add BuyTwoGetOneFreeTest
success BuyTwoGetOneFreePromotion calculate_test
add SecondHalfPricePromotionTest
success SecondHalfPricePromotion calculate_test
add DiscountPromotionTest
success DiscountPromotion calculate_test
Remove Middle Man
delete unuseful code
Extract newPromotionByType Method
delete unuseful code
rename newType method to newPromotionType
Remove doCalculate Method
format code
change date to DateTimeFormatter
Extract Method
update code
Merge branch 'master' of github.com:sorashiro/pos-java