quiz.rb

# COMMUNITY CHALLENGE
#
# How would you test this Quiz#problem method? Only two rules:
#
# 1. No mocks or stubs allowed. I'm looking for a other alternatives.
# Mocks can get messy in complex scenarios, and this is intended to
# be a high level test which executes all code. I don't think mocking
# would be a very clean solution anyway, but if you want to try it
# and prove me wrong feel free.
#
# 2. No changing the Quiz class implementation/structure. But you can
# use whatever framework you want for the tests.
#
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 "spec"
require "spec/autorun"

describe Quiz do
  before :each do
    @input  = mock(:input)
    @output = mock(:output)

    @quiz = Quiz.new(@input, @output)

    @quiz.stub!(:rand).and_return(1, 2)
  end

  it "should output 'Correct!' if the input is the sum of the two numbers given in the question" do
    @output.should_receive(:puts).ordered.with("What is 1 + 2?")
    @input.should_receive(:gets).ordered.and_return(3)
    @output.should_receive(:puts).ordered.with("Correct!")

    @quiz.problem
  end

  it "should output 'Incorrect!' if the input is not the sum of the two numbers given in the question" do
    @output.should_receive(:puts).ordered.with("What is 1 + 2?")
    @input.should_receive(:gets).ordered.and_return(4)
    @output.should_receive(:puts).ordered.with("Incorrect!")

    @quiz.problem
  end
end