pile.rb

pile.rb

# A Pile represents the pile of cards on the table during a card game

require 'card_list.rb'
require 'observer.rb'

class Pile
  include Observable
  
  attr_reader :last_card
  
  # Create an empty hand.
	def initialize
    @card_list = CardList.new
  end

  # Add card to pile.
  def add card
    @card_list.add card
    @last_card = card
    changed
    notify_observers(self)
  end

  # Empty the pile.
  def empty!
    @card_list.empty!
  end

  # Sort the pile.
  def sort!
    @card_list.sort
  end

  # Return pile as string
  def to_string
    @card_list.to_string
  end

  # iterate over all cards in pile
  def each
    @card_list.each{|card| yield card}
  end

  # Return number of cards in pile
  def no_of_cards
    @card_list.no_of_cards
  end

  # Return the best card in the pile
  def calculate_winner
    sorted_cards = @card_list.sort  # sort cards in 'poker' order
    sorted_cards[-1]                # return best card
  end

  # Return true iff top two cards of same suit
  def snap?
    if @cards.length < 2
      false
    # check for snap!
    elsif @cards[-1].suit == @cards[-2].suit
      true
    else
      false
    end
  end
end

TC_Pile.rb

require "test/unit"
require 'pile.rb'
require 'card.rb'
require 'winning_cards_observer.rb'

class TC_Pile < Test::Unit::TestCase

  def setup
    @pile = Pile.new
  end

  def test_initialisation
    assert_equal(0, @pile.no_of_cards)
  end

  def test_winner
    # create pile with entire pack of cards
    SUITS.each do |suit|
      KINDS.each do |kind|
        card = Card.new suit, kind
        @pile.add card
      end
    end
    # check that ace of spades is the winner
    ace_of_spades = Card.new :SPADES, :ACE
    assert_equal(ace_of_spades, @pile.calculate_winner)
  end
  
  
  def test_add_one_card
    @pile.empty!
    two_of_spades = Card.new :SPADES, :TWO
    @pile.add two_of_spades
    assert_equal(two_of_spades, @pile.last_card)
  end
  
  
  def test_observable 
    
    # create a new observer class
    wc_observer = WinningCardsObserver.new
    
    # add it to the pile's list of observers
    @pile.add_observer(wc_observer)
  
    #create a card and add it to the pile to trigger the notifyer
    two_of_spades = Card.new :SPADES, :TWO
    @pile.add two_of_spades
    
    # assert that the observer now knows the last card played
    assert_equal(two_of_spades, wc_observer.last_card)
      
  end

end

winning_cards_observer.rb

class WinningCardsObserver 

  attr_reader :last_card

  def update pile
    @last_card = pile.last_card
  end

end