hangman.rb

class Hangman
  LIST = ["canada", "england", "australia", "japan"]
  attr_accessor :word, :chances, :board, :list, :guesses, :answer

  class InvalidGuessException < Exception
  end  

  def initialize()
    @chances = 8
    @guesses = []
    @word    = LIST.sample
    #puts "WORD: ", @word
    @board   = setup_board(@word)
  end
  
  # return @guesses as a string
  def guesses
    @guesses.join(' ')
  end
    
  # if the word has the given letter, put it on the board, otherwise, it's a wrong guess
  def guess(letter)
    raise InvalidGuessException.new("Invalid Guess!") unless valid_guess?(letter)
    
    if word_has?(letter)
    	put_letter_on_board(letter)
    else
      wrong_letter(letter) if !@guesses.include? letter
    end
  end

  # return true if @board doesn't have a '_', otherwise return false
  def win?
    !@board.include? '_'
  end

  # return true if @chances is 0, otherwise return false
  def lost?
    @chances == 0
  end

  private

  def valid_guess?(letter)
    letter.length == 1
  end

  # replace indexes of @board with letter where the same indexes of @word are letter
  # in other words, if @board is _ _ _ _ _ _ and @word is canada
  # and the letter guessed is a
  # then @board should become _ a _ a _ a
  def put_letter_on_board(letter) # -> a
    for i in (0..@word.length)
      @board[i] = letter if @word[i] == letter
    end
  end

  # return true if word has letter
  def word_has?(letter)
    @word.include? letter
  end

  # return a string of underscores equal to length of the given word
  def setup_board(word)
    '_' * @word.length
  end

  # decrement # of chances and add letter to guesses
  def wrong_letter(letter)
    @chances -= 1
    @guesses << letter
  end
  
end

hangman_runner.rb

# require 'pry' <= Uncomment if you want to debug
require_relative "hangman"

#figure out a random word to use for the game
class HangmanRunner

  # Starts the hangman game
  def self.run 
    @game = Hangman.new()
    while true
      puts "\nBoard: #{@game.board}\n\n"
      puts "Guessed letters: #{@game.guesses}\n\n"
      puts "Chances: #{@game.chances}\n\n" 
      print "Take your best shot! Enter guess: "
      #binding.pry
      letter = gets.chomp
      
      # Hangman#guess may throw an exception when it's an invalid guess.
      begin
        @game.guess(letter)
      rescue Hangman::InvalidGuessException => e
        puts e.message
      end
      
      if @game.win?
        puts "\n\nCongratulations! You won!\n"
        break
      elsif @game.lost?
        puts "\n\nYou lost. The word was #{@game.word}\n"	
        break
      end
      puts "+++++++++++++++++++++++++++++++++++++++++++++++++++\n"
    end
  end
end 

HangmanRunner.run