Shopping Basket

We must be able to :

Add items to the shopping basket
Remove items from the shopping basket
Empty the shopping basket

Additionally, we must be able to calculate the total of the shopping basket accounting for:

Buy-one-get-one-free discounts on items
10% off on totals greater than £20 (after bogof)
2% off on total (after all other discounts) for customers with loyalty cards.

For more on the thinking behind the development see methinks.

Installation

You will need node v6+ installed:

git clone https://github.com/numical/shoppingbasket.git
cd shoppingbasket
npm i
npm test

The last command will write to console the full test suite.

Note that the a npm run debug option is available. For this to run you need:

no later than node v6.3.1 (due to this bug)
a global install of node-inspector

Usage

First, create items to buy using the ItemCatalogue. Creation also adds them to the catalogue:

const ItemCatalogue = require('./lib/ItemCatalogue');
...
const weetabix = ItemCatalogue.create(123456789, 'Weetabix - 500g', 199);
const marmite = ItemCatalogue.create(987654321, 'Marmite - 250g Squeezable', 219);

Then create a basket using ShoppingBasketand add/remove items:

const ShoppingBasket = require('./lib/ShoppingBasket');
...
const myBasket = ShoppingBasket.create();
myBasket.add(marmite, 2);
myBasket.add(weetabix);
myBasket.remove(marmite);

The total price of the basket is returned after each change and/or can be explicitly asked for. The price is given in pence; use a utiltiy function to display in pounds.

const displayInPounds = require('./lib/Util').displayInPounds;
...
const myBasket = ShoppingBasket.create();
let price = myBasket.add(marmite, 2); // 438
price = myBasket.add(weetabix); // 637 
price = myBasket.remove(marmite); // 418
price = myBasket.price();
price = displayInPounds(price) // "£4.18"

Discounts are automatically applied. However BOGOF (buy-one-get-one-free) offers must be set up on the DiscountEngine:

const DiscountEngine = require './lib/DiscountEngine';
...
DiscountEngine.addBOGOF(123456789);
...
let price = myBasket.add(weetabix, 2); // 199

The full API is defined here.

Licence

The MIT Licence (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.