Simple Ruby Tic Tac Toe

board.rb

class Board
  def initialize
    @rows = three_blank_rows
  end

  def playable_cell?(row, col)
    return false unless (1..3).cover?(row) && (1..3).cover?(col)
    @rows[col - 1][row - 1] == ' '
  end

  def play(row, col, string)
    @rows[col - 1][row - 1] = string
  end

  def to_s
    row_strings = @rows.map { |row| row.join(' | ') }
    row_strings.join("\n---------\n")
  end

  def winner
    players.find { |player| wins?(player) }
  end



  private

  def players
    @rows.flatten.uniq.delete_if { |cell| cell == ' ' }
  end

  def wins?(player)
    winnable_paths.any? { |path| completed_by?(player, path) }
  end

  def completed_by?(player, path)
    path.all? { |cell| cell == player }
  end

  def winnable_paths
    paths = @rows                                    # horizontal paths
    paths += @rows.transpose                         # vertical paths
    paths << [@rows[0][0], @rows[1][1], @rows[2][2]] # ascending diagonal path
    paths << [@rows[0][2], @rows[1][1], @rows[2][0]] # descending diagonal path
    paths
  end

  def three_blank_rows
    Array.new(3) { blank_row }
  end

  def blank_row
    Array.new(3, ' ')
  end
end

play.rb

require_relative 'board'

def get_play_choices
  puts "Enter the row you'd like to play in (from 1 to 3)."
  row = gets.chomp.to_i
  puts "Enter the column you'd like to play in (from 1 to 3)."
  column = gets.chomp.to_i

  [row, column]
end

board = Board.new

turn = 1
until board.winner
  player = turn.odd? ? 'X' : 'O'

  puts "Play your turn, player #{player}.\n"

  row, column = get_play_choices

  until board.playable_cell?(row, column)
    puts "You can't play there.\n"
    row, column = get_play_choices
  end

  board.play(row, column, player)

  puts "#{board}\n"
  turn += 1
end

puts "#{board.winner} wins!"