Kata #6: Battleship https://en.wikipedia.org/wiki/Battleship_(game)

battleship.rb

require 'pry'

class Battleship
  DEFAULT_ROWS_COUNT    = 10
  DEFAULT_COLUMNS_COUNT = 10
  VERTICAL              = 'ns'.freeze
  HORIZONTAL            = 'ew'.freeze
  HIT                   = '*'.freeze
  MISS                  = 'x'.freeze

  class Ship
    attr_reader :player, :row, :column, :length, :orientation

    def initialize(player:, row:, column:, length:, orientation:)
      @player      = player
      @row         = row
      @column      = column
      @length      = length
      @orientation = orientation

      # http://www.midwestconnection.org/glshpng/glossary.htm
      def hull
        orientation == Battleship::VERTICAL ? populate_vertically : populate_vertically
      end
    end
  end

  attr_reader :rows, :columns, :ships

  def initialize(rows: DEFAULT_ROWS_COUNT, columns: DEFAULT_COLUMNS_COUNT)
    @rows = rows
    @columns = columns
    @ships = []
  end

  def add_ship(player:, row:, column:, length:, orientation:)
    ship = Ship.new(player: player, row: row, column: column, length: length, orientation: orientation)
    ships << ship

    ship
  end

  def ships_for(player:)
    ships.select { |ship| ship.player == player }
  end

  def attack(player:, row:, column:)
    #
  end

  # board_status
  def board(player:, row:, column:)
    ships_for(player: player).select { |ship| ship.row == row && ship.column == column }
  end
end

Gemfile

source 'https://rubygems.org'

gem 'minitest'
gem 'pry-byebug'

run.rb

require './battleship.rb'
require 'minitest/autorun'
require 'pry'

describe Battleship do
  def battleship
    @battleship ||= Battleship.new(**board_size)
  end

  def board_size
    @board_size ||= { rows: 10, columns: 10 }
  end

  describe 'initialization' do
    it "sets the board's rows" do
      assert_equal board_size[:rows], battleship.rows
    end

    it "sets the board's columns" do
      assert_equal board_size[:columns], battleship.columns
    end
  end

  describe '#add_ship' do
    it 'adds a ship at the given coordinates' do
      battleship.add_ship(player: 1, row: 3, column: 4, length: 5, orientation: Battleship::VERTICAL)

      refute_empty battleship.ships_for(player: 1)

      battleship.ships_for(player: 1).each do |ship|
        assert_equal 1, ship.player
        assert_equal 3, ship.row
        assert_equal 4, ship.column
        assert_equal 5, ship.length
        assert_equal Battleship::VERTICAL, ship.orientation
      end
    end
  end

  describe '#attack' do
    it 'records a miss' do
      row     = 5
      column  = 5
      result  = battleship.attack(player: 1, row: row, column: column)

      assert_equal Battleship::MISS, result
      assert_equal Battleship::MISS, battleship.board(player: 1, row: row, column: column)
    end

    it 'records a hit' do
      row     = 5
      column  = 5
      ship    = battleship.add_ship(player: 1, row: row - 1, column: column, length: 5, orientation: Battleship::VERTICAL)
      result  = battleship.attack(player: 1, row: row, column: column)

      assert_equal Battleship::HIT, result
      assert_equal Battleship::HIT, battleship.board(player: 1, row: row, column: column)
    end
  end
end