public void AddProductItem(ProductCode prodCode, ProductQuantity quantity)
{
if (prodCode == null)
{
throw new ArgumentNullException(nameof(prodCode));
}
if (quantity == null)
{
throw new ArgumentNullException(nameof(quantity));
}
// kontrola invariantu agregatu
var item = TryGetInvoiceItem(prodCode);
if (item != null)
{
throw new InvalidOperationException($"Invoice item already exists for product code {prodCode}");
}
_items[prodCode] = new InvoiceItem(prodCode, quantity);
}
public InvoiceItem(ProductCode productCode, ProductQuantity productQuantity)
{
ProductCode = productCode ?? throw new ArgumentNullException(nameof(productCode));
ProductQuantity = productQuantity ?? throw new ArgumentNullException(nameof(productQuantity));
}