Contents

# frozen_string_literal: true

if RUBY_VERSION <= '3.1'
  puts 'This example requires Ruby 3.1 or higher.'
  exit! 1
end

require_relative 'config'

task :default do
  puts '==================='
  puts 'Design by Contract '
  puts '==================='
  puts

  cart = ShoppingCart.new

  puts '--  Adding items  --'
  puts

  cart.add_item('Apple', 5, 1.5)

  puts "Total Price: $#{cart.total_price}"
  puts

  puts '--  Removing items  --'
  puts

  cart.remove_item('Apple', 2)

  puts "Total Price: $#{cart.total_price}"
  puts

  puts '--  Invalid input  --'
  puts

  begin
    cart.remove_item('Apple', 4)
  rescue StandardError => e
    puts e.message
  end

  puts
  puts '--------------------------------------------'
  puts '--  Violating the invariant deliberately  --'
  puts '--------------------------------------------'
  puts

  [
    -> { cart.instance_variable_set(:@items, { 'Apple' => { quantity: [-1, '1'].sample, price_per_unit: 1.5 } }) },
    -> { cart.instance_variable_set(:@items, { 'Apple' => { quantity: 1, price_per_unit: [-1.5, '1.5'].sample } }) },
    -> { cart.instance_variable_set(:@items, { ['', nil].sample => { quantity: 1, price_per_unit: 1.5 } }) }
  ].sample.call

  [
    -> { cart.add_item('Orange', 1, 1) },
    -> { cart.remove_item('Apple', 1) },
    -> { cart.total_price }
  ].sample.call
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
bcdd-contract-0.1.0	examples/design_by_contract/Rakefile