player_factory.rb

require 'tictactoe_constants'

  class PlayerFactory
    include TictactoeConstants
    attr_accessor :player_one, :player_two
    def initialize(type_one, type_two)
      @player_one = create_player(type_one, TictactoeConstants::MARKER_X)
      @player_two = create_player(type_two, TictactoeConstants::MARKER_O)
      set_opponents
    end

    def create_player(type, marker)
      case type
      when TictactoeConstants::COMPUTER_PLAYER
        ComputerPlayer.new(marker)
      when TictactoeConstants::HUMAN_PLAYER
        HumanPlayer.new(marker)
      when TictactoeConstants::AI_PLAYER
        AIPlayer.new(marker)
      else
        raise "Invalid player type"
      end
    end
  ...
end