Start of DSL for shopping cart and sales from SCIL #7 by @TzipiZnavot, @eladsof & @AvivBY

cart_dsl.rb

describe 'cart' do
  it 'allows discount after purchasing certain amount' do
    product = Product.new('Snickers', 3)
    cart = Cart.new
    
    6.times { cart << product }

    cart.when_buying(product).times(5).get(1).free()

    cart.total.should == 5*3
  end
end

Product = Struct.new(:name, :price)

class Rule
  def initialize(product)
    @product = product
  end

  def times(count)
    @times = count
    self
  end

  def get(benefit_count)
    @benefit_count = benefit_count
    self
  end

  def free
    @discount = 1
    self
  end

  def apply_for(products)
    return @benefit_count * @product.price * @discount if applies_for? products

    0
  end

  def applies_for?(products)
    products.count {|p| p == @product} >= @times + @benefit_count
  end
end

class Cart
  def initialize
    @products = []
    @rules = []
  end

  def regular_total
    @products.map(&:price).inject(&:+)
  end

  def benefits
    @rules.map { |rule| rule.apply_for(@products) }.inject(&:+)
  end

  def total
    regular_total - benefits
  end

  def <<(product)
    @products << product
  end

  def when_buying(product)
    rule = Rule.new(product)
    @rules << rule
    rule
  end
end

@products.map { |p| p.price }.inject(&:+) can be written  @products.map(&:price).inject(&:+)

apply_for(products) can be
return @benif.....@Discount if applies_for? products
0

Other than that - the Rule class seems kinda off but i can't quite put my finger on it...