public PickedUpBasket AddProduct(ProductId productId)
{
return (PickedUpBasket) Apply(this, new ProductAddedToBasket(
BasketId.ToString(),
productId.ToString()
));
}
void AssertContainsProduct(ProductId productId)
{
if ( ! ProductsInBasket.Contains(productId)) {
throw new ProductNotInBasketException(string.Format(
"Product with id {0} is not in the basket",
productId
));
}
}
public PickedUpBasket RemoveProduct(ProductId productId)
{
AssertContainsProduct(productId);
return (PickedUpBasket) Apply(this, new ProductRemovedFromBasket(
BasketId.ToString(),
productId.ToString()
));
}