quiz.rb

# COMMUNITY CHALLENGE
#
# How would you test this Quiz#problem method? Only two rules:
#
# 1. The tests should fail if any part of the application breaks.
#    For example: If "gets" is moved before "puts" then the tests should
#    fail since that breaks the application.
#
# 2. You cannot change the Quiz class. But you can use whatever framework
#    and tools you want for the tests. (RSpec, Cucumber, etc.)
# 
# Note: The first rule used to be "no mocking" but I changed it. If you
#       can accomplish the first rule with mocks then go ahead. I'm looking
#       for the simplest/cleanest solution whatever that may be.
#
class Quiz
  def initialize(input = STDIN, output = STDOUT)
    @input = input
    @output = output
  end
  
  def problem
    first = rand(10)
    second = rand(10)
    @output.puts "What is #{first} + #{second}?"
    answer = @input.gets
    if answer.to_i == first + second
      @output.puts "Correct!"
    else
      @output.puts "Incorrect!"
    end
  end
end

require "rubygems"
require "test/unit"
require "shoulda"

class QuizIO
  attr_accessor :response, :should_calculate

  def gets
    if @should_calculate && @response =~ /What is (\d+) \+ (\d+)\?/
      return $1.to_i + $2.to_i
    else
      return -1
    end
  end

  def puts(s)
    @response = s
  end
end

class QuizTest < Test::Unit::TestCase
  context "A Quiz" do
    setup do
      @io = QuizIO.new
      @quiz = Quiz.new(@io, @io)
    end

    context "given a correct answer" do
      setup { @io.should_calculate = true ; @quiz.problem }
      should "get a 'Correct!' response" do
        assert_equal 'Correct!', @io.response
      end
    end
    
    context "given an incorrect answer" do
      setup { @io.should_calculate = false ; @quiz.problem }
      should "get an 'Incorrect!' response" do
        assert_equal 'Incorrect!', @io.response
      end
    end
  end
end