create package service and test ItemServiceTest
delete interface test
create test ItemServiceTest
create interface ItemService
rename ItemServiceTest to ItemServiceTestImpl
finish interface ItenService
create class ItemServiceImpl and implements interface method
test and implement getItem at service
finish getItem at service and test pass
test and implement getItems at service
finish getItems at service and test pass
create class CategoryDao
finish interface CategoryDao and implements class CategoryImpl
finish CategoryImpl.java
rename CategoryImpl to CategoryDaoImpl
create interface CategoryService
finish interface CategoryService.java
create test CategoryServiceImplTest
create CategoryServiceImpl and implements test
finish getCategory at CategoryService and test pass