modify Product
add ProductDao
add test ProductDaoTest
add test should_return_productList method
add fields id
modify Product constructor
add test CategoryDaoTest
add test should_return_categoryList method
add mysql jar
modify product test
add promotionDaoTest
add test should_return_promotionTypes
add PromotionDao
add getPromotionTypes method
modify test should_return_a_product_list method
add test should_return_category_when_input_id method
modify getCategory method
add test should_return_types_when_input_productId method
modify getPromotionTypes method
remove useless test method