Card.rb

class Card
  attr_reader :suit
  attr_reader :value

  def initialize(value, suit)
    get_suit(suit)
    get_value(value)
  end

  def get_suit(suit) # gets the suit, but rejects invalid suits
    if [:♠, :♦, :♣, :♥].include?(suit)
      @suit = suit
    else
      fail(ArgumentError, 'not a valid suit')
    end
  end

  def get_value(value) # gets the value, but rejects invalid values.
    @value = value
    @value = :A if value == 1
    @value = :J if value == 11
    @value = :Q if value == 12
    @value = :K if value == 13
    if value < 1 || value > 13
      fail(ArgumentError, 'not a valid value for a card')
    end
  end
end