public void AddItemToCheckout(int sku, decimal quantity, MeasurmentUnits buyUnit, DiscountRule discountRule)
{
// First get the product with the corresponding SKU from repository
var product = _productsRepo.GetProduct(sku);
if (product == null)
{
throw new ArgumentException($"Cannot find product with SKU : {sku}");
}
if (product.UnitPrice <= 0)
{
throw new ArgumentOutOfRangeException("Cannot add a product with invalid price");
}
if (quantity <= 0)
{
throw new ArgumentOutOfRangeException("Cannot add a product with negative or zero quantity");
}
if (product.MeasurmentUnit == MeasurmentUnits.PIECE && quantity != Math.Round(quantity))
{
throw new ArgumentException("Cannot add product sold by number with a floating decimal quantity");
}
if (product.MeasurmentUnit != buyUnit)
{
try
{
// get the quantity corresponding to the sell unit, rounded to 3 decimals
quantity = Math.Round(GetQuantityFromUnit(quantity, product.MeasurmentUnit, buyUnit), 3);
}
catch (Exception e)
{
throw new ArgumentException(e.Message + $": Sell Unit {product.MeasurmentUnit}, Buy Unit {buyUnit}");
}
}
if (discountRule != null)
{
discountRule = ConfigureDiscountRuleParams(discountRule.Id, product.UnitPrice);
}
// Finally add a "quantity" of this product to the list of
// checkout items if all the checking conditions are met
_checkoutRepo.AddItem(product, quantity, buyUnit, discountRule);
}
public void AddItem(Product product, decimal quantity, MeasurmentUnits buyUnit, DiscountRule discountRule)
{
product.DiscountRule = discountRule;
// create a CheckoutItem object from the provided parameters
var checkoutItem = new CheckoutItem
{
Product = product,
Quantity = quantity,
BuyUnit = buyUnit,
Price = product.UnitPrice * quantity
};
// Set a unique ID and increment the static counter
checkoutItem.Id = _id;
Interlocked.Increment(ref _id);
// add the item to the checkout list
_checkoutItems.Add(checkoutItem);
}
[InlineData(4, 800, MeasurmentUnits.MILLILITRE, 1)] // item with SKU = 4 costs $1.25/litre (so what does 800 millilitres cost?)
public void Test_CanCalculateTotalSingleItemPerWeightOrVolume(int id, decimal quantity, MeasurmentUnits buyUnit, decimal expectedPrice)
{
var checkoutService = Subject();
// add the sequence of inline data
checkoutService.AddItemToCheckout(id, quantity, buyUnit, null);
// verify that the calulated price is equal to the expected price
Assert.Equal(expectedPrice, checkoutService.CalculateTotal());
}
// returns the quantity equivalent to sell unit based on the buy unit
private decimal GetQuantityFromUnit(decimal quantity, MeasurmentUnits saleUnit, MeasurmentUnits buyUnit)
{
string message = "Not compatible buy and sell units";
switch (saleUnit)
{
/***** Mass Conversion *****/
// Convert to pounds
case MeasurmentUnits.POUND:
if (buyUnit == MeasurmentUnits.OUNCE)
{
return(MassConversion.OuncesToPounds(quantity));
}
if (buyUnit == MeasurmentUnits.GRAM)
{
return(MassConversion.GramsToPounds(quantity));
}
if (buyUnit == MeasurmentUnits.KILOGRAM)
{
return(MassConversion.KilogramsToPounds(quantity));
}
else
{
throw new ArgumentException(message);
}
// Convert to Kilograms
case MeasurmentUnits.KILOGRAM:
if (buyUnit == MeasurmentUnits.GRAM)
{
return(MassConversion.GramsToKilograms(quantity));
}
if (buyUnit == MeasurmentUnits.POUND)
{
return(MassConversion.PoundsToKilograms(quantity));
}
if (buyUnit == MeasurmentUnits.OUNCE)
{
return(MassConversion.OuncesToKilograms(quantity));
}
else
{
throw new ArgumentException(message);
}
// Convert to Grams
case MeasurmentUnits.GRAM:
if (buyUnit == MeasurmentUnits.OUNCE)
{
return(MassConversion.OuncesToGrams(quantity));
}
if (buyUnit == MeasurmentUnits.POUND)
{
return(MassConversion.PoundsToGrams(quantity));
}
if (buyUnit == MeasurmentUnits.KILOGRAM)
{
return(MassConversion.KilogramsToGrams(quantity));
}
else
{
throw new ArgumentException(message);
}
// Convert to ounces
case MeasurmentUnits.OUNCE:
if (buyUnit == MeasurmentUnits.POUND)
{
return(MassConversion.PoundsToOunces(quantity));
}
if (buyUnit == MeasurmentUnits.GRAM)
{
return(MassConversion.GramsToOunces(quantity));
}
if (buyUnit == MeasurmentUnits.KILOGRAM)
{
return(MassConversion.KilogramsToOunces(quantity));
}
else
{
throw new ArgumentException(message);
}
/***** Volume Conversion *****/
case MeasurmentUnits.LITRE:
if (buyUnit == MeasurmentUnits.GALLON)
{
return(VolumeConversion.GallonsToLitres(quantity));
}
if (buyUnit == MeasurmentUnits.MILLILITRE)
{
return(VolumeConversion.MillilitresToLitres(quantity));
}
else
{
throw new ArgumentException(message);
}
case MeasurmentUnits.GALLON:
if (buyUnit == MeasurmentUnits.LITRE)
{
return(VolumeConversion.LitresToGallons(quantity));
}
if (buyUnit == MeasurmentUnits.MILLILITRE)
{
return(VolumeConversion.MillilitresToGallons(quantity));
}
else
{
throw new ArgumentException(message);
}
case MeasurmentUnits.MILLILITRE:
if (buyUnit == MeasurmentUnits.LITRE)
{
return(VolumeConversion.LitresToMillilitres(quantity));
}
if (buyUnit == MeasurmentUnits.GALLON)
{
return(VolumeConversion.GallonsToMillilitres(quantity));
}
else
{
throw new ArgumentException(message);
}
default:
throw new ArgumentException(message);
}
}
