Extension of Rob Olson’s ruby-poker gem¶ ↑

Additions:

- command-line interface

- spec-style tests w/ updated Rake task

- test-driven development of extensions

- card.rb
    1) new class method that generates a random card

- poker_hand.rb
    1) new class method that generates a hand of random cards
    2) new instance method that mocks the user if they miss a royal
       flush by 1 card

- poker_game.rb
    1) new class that handles individual poker games
    2) will track username and bet amounts (NYI)