This application is used to take in an input of items in a shopping cart, and a list of price rules. The application will then apply the price rules to the items and calculate the price sent on each item and the total price of the transaction. The system will always calculate the lowest possible price for the transaction. The shopping cart and price rules should both be defined in files. These files can be changed while the application is running and each distinct run will apply the latest rules and cart.
The input for the shopping cart and the price rules should be placed in their own file and
encoded in a standard string format a .txt file is recommended. See the *-example files for a visual example.
The names of items and commands are case-insensitive.
The format of items in the cart file is that each item should be placed on its own line. For example
Apple
Apple
This will add two apples to the cart. If the input was Apple,Apple or AppleApple. This will not function as expected. This will produce the items Apple,Apple and AppleApple
This application currently supports four different commands for the pricing of items. Each command tuple should be on its own line, and a comma should separate the command from the target item.
The first is to set a regular price of an item. This is required for all items in the system. If an item does not have a
regular price the system will throw an error and exit. The format of this command is X.XX,ITEM . The number set
for the price must be positive and at least 0.01. The system will also truncate prices to 2 decimal places as this is
convention with currency.
The system will accept a command to apply a discount of buy one, get one free. The format of this command
is BOGO,ITEM. If an odd number of items are in the cart, and the bogo is applied you will not receive any discount
in the final item.
The system will accept a command to apply a discount of 50% to a second item when an item is purchased at full price.
The format of this command is BO50,ITEM. That is B O Five Zero. If there are an odd number of items to apply the
discount to then the final item will be applied at full price.
The system will accept a command to apply a special price for a lot of items. An example of this is buy three apples for a
dollar. The format of this command is XFY,ITEM. Where X is the size of the lot required to apply the discount and
Y is the price of the lot. This discount will only be applied if it provides a better price than the regular price of
the item
The system is currently implemented to only work with a single discount available for each item. If multiple discounts are set for an item, the system will not error, but the guarantee of the lowest price calculation is no longer valid.
If there is a BOGO deal on an item, and an odd number of items exists in the cart, the customer will receive the item at regular price. This situation brings a question should the customer have another one of the items added to their cart? They have technically paid for it. There is also the option of having the item be discounted by 50%. The system could also notify them and let the customer decide.
Currently, if a price rule for an item is defined twice then the system will use the one defined later in the files. For example if you set a three for five rule on apples and then later in the file you set a two for five. The system will use the two for five rule as it was defined later.
This application requires a full installation of python3 to run. It requires sys,os and unittest from the standard python library.
To run the application in interactive mode
python3 checkout_application.py <Rules-File> <Cart-File>
To run the unit tests
python3 checkout_application_tests.py