Learning about minitest from Steve Klabnik

register.rb

require 'minitest/autorun'

class TestCashRegister < MiniTest::Unit::TestCase 
  def setup
    @register = CashRegister.new
  end
  def test_default_is_zero
    assert_equal 0, @register.total
  end
  def test_total_calculation
    @register.scan 1
    @register.scan 2
    assert_equal 3, @register.total
  end
  def test_total_is_zero_after_clear
    @register.scan 1
    @register.clear
    assert_equal 0, @register.total
  end
end

class CashRegister
  def initialize
    @items = []
  end
  def total
    @items.inject(0, &:+)
  end
  def scan(item)
    @items << item
  end
  def clear
    @items = []
  end
end

Thanks for sharing this code... :)