quiz.rb

# COMMUNITY CHALLENGE
#
# Here's my (@ljsc) solution.  I guess this would qualifiy as a mock.
#
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
  class Responder
    def initialize; @queue = [] end
    def to_a; [self, self] end
    attr_reader :gets
    
    def expect(pattern, &blk)
      @queue << [pattern, blk]
    end
    
    def puts(str)
      pattern, handler = @queue.shift
      if match = str.match(pattern)
        @gets = handler[*match] if handler
      else
        raise Test::Unit::AssertionFailedError, %Q[#{str.inspect} did not match #{pattern.inspect}]
      end
    end
  end

  def setup
    @responder = Responder.new
    @quiz = Quiz.new(*@responder)
  end

  def test_correct
    @responder.expect %r[What is (\d+) \+ (\d+)?] do |_, a, b|
      a.to_i + b.to_i
    end
    @responder.expect 'Correct!'
    @quiz.problem
  end
  
  def test_incorrect
    @responder.expect %r[What is (\d+) \+ (\d+)?] do |_, a, b|
      a.to_i + b.to_i + 1
    end
    @responder.expect 'Incorrect!'
    @quiz.problem
  end
end