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

######################################################################
# SOLUTION 2 - Using mocks
######################################################################

require 'rubygems'
require 'test/unit'
require 'shoulda'
require 'flexmock/test_unit'

class QuizTestWithMocks < Test::Unit::TestCase
  context "A Quiz" do
    setup do
      @mock_io = flexmock("IO")
      @mock_io.should_receive(:puts).with("What is 2 + 3?").once.ordered
      @quiz = Quiz.new(@mock_io, @mock_io)
      flexmock(@quiz).should_receive(:rand).and_return(2, 3)
    end

    context 'when given the correct answer' do
      setup do
        @mock_io.should_receive(:gets).and_return("5\n").once.ordered
      end

      should 'receive a Correct response' do
        @mock_io.should_receive(:puts).with("Correct!").once.ordered
        @quiz.problem
      end
    end

    context 'when given an incorrect answer' do
      setup do
        @mock_io.should_receive(:gets).and_return("6\n").once.ordered
      end

      should 'receive an Incorrect response' do
        @mock_io.should_receive(:puts).with("Incorrect!").once.ordered
        @quiz.problem
      end
    end
  end
end