experiment with Avdi's poker problem

Inspired by the challenge posed by
[RubyTapas Episode 472](https://www.rubytapas.com/2017/03/27/episode-472-contextual-identity/)

I paired with @pachonk to work up to this point.
We implemented a Deck class which
extends beyond what Avdi's minimalistic approach
begins with.
Looking forward to seeing what Avdi's recommended
approach looks like.

poker.rb

@@ -0,0 +1,67 @@
+#! /usr/bin/env ruby
+
+puts "let's play some poker"
+
+class Card
+  attr_reader :rank, :suit
+  attr_reader :player
+
+  def initialize(suit, rank)
+    @rank = rank
+    @suit = suit
+  end
+
+  def player=(object)
+    @player = object.object_id
+  end
+
+  include Comparable
+  def <=>(other)
+    [rank, suit] <=> [other.rank, other.suit]
+  end
+
+  def inspect
+    "#{self.class}: #{rank} of #{suit}"
+  end
+  def to_s; inspect; end
+end
+
+class Deck
+  attr_reader :cards
+
+  def initialize
+    @cards = %w[Hearts Spades Clubs Diamonds]
+              .product((1..13).to_a)
+              .map{|r,s| Card.new(r,s) }
+  end
+
+  def ==(other)
+    self.cards == other.cards
+  end
+
+  def sort
+    cards.sort
+  end
+
+  def shuffle
+    self.cards = cards.shuffle
+    return self
+  end
+
+  def deal(player, count = 1)
+    raise ArgumentError, 'deal count must be an integer' unless count.is_a? Integer
+
+    cards.select {|card| card.player == nil }
+         .take(count)
+         .each { |card| card.player = player }
+  end
+
+  def show_hand(object)
+    cards.select {|card| card.player == object.object_id }
+  end
+
+  private
+
+  attr_writer :cards
+end
+

poker_test.rb

@@ -0,0 +1,85 @@
+#! /usr/bin/env ruby
+
+require 'minitest/autorun'
+require_relative 'poker'
+
+class CardTest < Minitest::Test
+  def test_exists
+    Card
+  end
+end
+
+class DeckTest < Minitest::Test
+  def test_exists
+    Deck
+  end
+
+  def test_deal_does_not_accept_non_integer
+    deck = Deck.new
+    assert_raises(ArgumentError) { deck.deal(:p1, 'hi') }
+  end
+
+  def test_deal_takes_number_of_cards_to_deal
+    deck = Deck.new
+    assert_equal 5, deck.deal(:p1, 5).length
+  end
+
+  def test_deal_uses_one_by_default
+    deck = Deck.new
+    assert_equal 1, deck.deal(:p1).length
+  end
+
+  def test_deal_returns_an_array_of_cards
+    deck = Deck.new
+    assert deck.deal(:p1, 4).all? {|card| card.is_a? Card }
+  end
+
+  def test_shuffle_scrambles_deck_cards
+    reference_deck = Deck.new
+    deck = Deck.new
+    deck.shuffle
+    refute deck.cards == reference_deck.cards
+  end
+
+  def test_can_never_have_more_than_fifty_two_cards
+    skip
+  end
+
+  def test_can_never_have_less_than_fifty_two_cards
+    skip
+  end
+
+  def test_can_not_have_duplicate_cards
+    skip
+    reference_deck = Deck.new.sort
+    played_deck = Deck.new.shuffle
+    stacks = []
+    5.times { stacks << played_deck.deal(5) }
+    game_deck = stacks.reduce(:+).sort
+
+    assert reference_deck.cards == game_deck.cards
+  end
+
+  def test_cannot_deal_more_cards_than_deck_has
+    skip
+  end
+
+  def test_show_hand_returns_a_players_hand
+    deck = Deck.new
+
+    deck.deal(:p1, 26)
+
+    assert_equal 26, deck.show_hand(:p1).count
+
+    deck.deal(:p2, 26)
+
+    assert_equal 26, deck.show_hand(:p2).count
+
+    cheat_cards = deck.show_hand(:p1).count do |card|
+      deck.show_hand(:p2).include?(card)
+    end
+
+    assert_equal 0, cheat_cards
+  end
+end
+