could be better, could be worser

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 "test/unit"

class QuizTest < Test::Unit::TestCase
  def new_quiz(*args)
    Quiz.new(*args)
  end

  class EagerQuizIO < StringIO
    def initialize(buffer, &block)
      @algorithm = block
      super
    end

    def puts(*args)
      super
      first, second = args.first.scan(/\d+/).flatten
      first and second ?
        @answer = @algorithm.call(first.to_i, second.to_i) : nil
    end

    def gets
      @answer || super
    end
  end

  def test_correct
    io = EagerQuizIO.new(result='') { |x, y| x + y }
    quiz = new_quiz(io, io)
    quiz.problem
    assert result.include?('Correct!')
  end

  def test_incorrect
    io = EagerQuizIO.new(result='') { |x, y| x + y + 1 }
    quiz = new_quiz(io, io)
    quiz.problem
    assert result.include?('Incorrect!')
  end
end