public ShoppingListUpdateService(IShoppingListRepository shoppingListRepository,
                                  IAddItemToShoppingListService addItemToShoppingListService)
 {
     this.shoppingListRepository       = shoppingListRepository;
     this.addItemToShoppingListService = addItemToShoppingListService;
 }
 public AddItemToShoppingListCommandHandler(IShoppingListRepository shoppingListRepository,
                                            IAddItemToShoppingListService addItemToShoppingListService)
 {
     this.shoppingListRepository       = shoppingListRepository;
     this.addItemToShoppingListService = addItemToShoppingListService;
 }