README

Notes

• Project doesn't have Gemfile because is using only ruby stdlib.
• Item model validation is out of scope.

How to test

  > bin/example.rb 001 002 003
  Adding item: Lavender heart - 9.25
  Adding item: Personalised cufflinks - 45.0
  Adding item: Kids T-shirt - 19.95
  Your order total is: £66.78

APIs overview

Checkout

  checkout = Checkout.new(rules)
  checkout.scan(item)
  checkout.total

Rule engine

To add rule

  rules = SimpleRuleEngine.new
  rules.add_rule do |rule|
    rule.name = 'Lavender hearts discount'
    rule.priority = 10
    rule.when do |items|
      items.select { |item| item.product_code == '001' }.length > 1
    end
    rule.then do |items|
      items.each do |item|
        item.price = 8.5 if item.product_code == '001'
      end
    end
  end

List rules

  rules.list_rules # [{name: 'Rule', priority: 1}]

Reset/clear rules

  rules.reset_rules!

Execute rules

  rules.call(objects_to_be_processed)