README.md

Cashier

A simple cashier function that adds products to a cart and displays the total price.

Interface

co = Checkout.new(pricing_rules)
co.scan(item)
co.scan(item)
price = co.total

Create items like this:

Item.new(product_number: '123', name: 'My item', price: 3.5)

By default, there are three pricing rules defined:

• Pricing::GetOneFreeAfterN
• Pricing::PriceDiscountAfterN
• Pricing::PriceDropAfterN

To add a new one, just inherit the Discount::BaseDiscount and define the #apply method at least.

module Pricing
  class NewFancyPricingRule < BasePricingRule
    def apply(items, total)
      # do calculations & return reduced price
    end
  end
end

Test products

Product code	Name	Price
GR1	Green tea	£3.11
SR1	Strawberries	£5.00
CF1	Coffee	£11.23

Special conditions:

• The CEO is a big fan of buy-one-get-one-free offers and of green tea. He wants us to add a rule to do this.
• The COO, though, likes low prices and wants people buying strawberries to get a price discount for bulk purchases. If you buy 3 or more strawberries, the price should drop to £4.50
• The CTO is a coffee addict. If you buy 3 or more coffees, the price of all coffees should drop to two thirds of the original price.

Test data:

• Basket: GR1,SR1,GR1,GR1,CF1
  • Total price expected: ​£22.45
• Basket: GR1,GR1
  • Total price expected: ​£3.11
• Basket: SR1,SR1,GR1,SR1
  • Total price expected:​ £16.61
• Basket: GR1,CF1,SR1,CF1,CF1
  • Total price expected:​ £30.57