Answer to Headshift's Rails Test

Checkout

# encoding: UTF-8
class Checkout

  @@current_items = {}
  @@stock_items = {}

  def initialize(pricing_rules)
    # Sets the current_items hash to store the amount/type of items
    set_items(pricing_rules)
  end

  def scan(item)
    # Iterate over each key to check if it's available and add an item to it
    @@current_items.each do |key, value|
      if key == item.upcase.to_sym
        @@current_items[key] += 1
      end
    end
  end

  def total
    # Apply the offers rules before calculating the total
    apply_offer_rules
    total = 0
    @@current_items.each do |key,value|
      total += (value * @@stock_items[key]).round(2)
    end
    humanize_total(total)
  end

  private
  # Prepare both the @@current_items and @@stock_items hashes with the
  # pricing_rules
  def set_items(pricing)
    pricing.each do |key, value|
      @@current_items[key.to_sym] = 0
      @@stock_items[key.to_sym] = value
    end
  end

  def humanize_total(amount)
    puts "€" + amount.to_s
  end

  def apply_offer_rules
    # If you buy more than 2 strawberries price drops to 4.50
    if @@current_items[:SR1] > 2
       @@stock_items[:SR1]= 4.50
    end
    # If you have an even amount of Fruit tea cut down the price by hal
    # Otherwise drop the price and add one item because you get one free :-)
    if @@current_items[:FR1].even?
      @@stock_items[:FR1] =  @@stock_items[:FR1] / 2
    else
      @@stock_items[:FR1] =  @@stock_items[:FR1] / 2
      @@current_items[:FR1] += 1
    end

  end

end

rules = {:FR1 => 3.11, :SR1 => 5.00, :CF1 => 11.23 }

co1 = Checkout.new(rules)

# Basket: SR1,SR1,FR1,SR1
co1.scan('sr1')
co1.scan('sr1')
co1.scan('fr1')
co1.scan('sr1')
co1.total

co1 = Checkout.new(rules)

# Basket: FR1,FR1
co1.scan('fr1')
co1.scan('fr1')
co1.total

co1 = Checkout.new(rules)

# Basket: FR1,SR1,FR1,FR1,CF1

co1.scan('fr1')
co1.scan('sr1')
co1.scan('fr1')
co1.scan('fr1')
co1.scan('cf1')

co1.total