/**
* <remarks>
* This method supports chaining
* </remarks>
*
* <exception cref="ProductNotFoundException">
* Thrown when productCode does not exist in data source
* </exception>
*/
public PointOfSaleTerminal ScanProduct(string productCode)
{
var product = dataSource.FindProduct(productCode: productCode);
if (product == null)
{
throw new ProductNotFoundException($"Product {productCode} does not exist");
}
cart.Add(product);
return(this);
}