# rootulp's solution

## to Bowling in the Ruby Track

Published at Jul 13 2018 · 1 comment
Instructions
Test suite
Solution

#### Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

Score a bowling game.

Bowling is a game where players roll a heavy ball to knock down pins arranged in a triangle. Write code to keep track of the score of a game of bowling.

## Scoring Bowling

The game consists of 10 frames. A frame is composed of one or two ball throws with 10 pins standing at frame initialization. There are three cases for the tabulation of a frame.

• An open frame is where a score of less than 10 is recorded for the frame. In this case the score for the frame is the number of pins knocked down.

• A spare is where all ten pins are knocked down by the second throw. The total value of a spare is 10 plus the number of pins knocked down in their next throw.

• A strike is where all ten pins are knocked down by the first throw. The total value of a strike is 10 plus the number of pins knocked down in the next two throws. If a strike is immediately followed by a second strike, then the value of the first strike cannot be determined until the ball is thrown one more time.

Here is a three frame example:

Frame 1 Frame 2 Frame 3
X (strike) 5/ (spare) 9 0 (open frame)

Frame 1 is (10 + 5 + 5) = 20

Frame 2 is (5 + 5 + 9) = 19

Frame 3 is (9 + 0) = 9

This means the current running total is 48.

The tenth frame in the game is a special case. If someone throws a strike or a spare then they get a fill ball. Fill balls exist to calculate the total of the 10th frame. Scoring a strike or spare on the fill ball does not give the player more fill balls. The total value of the 10th frame is the total number of pins knocked down.

For a tenth frame of X1/ (strike and a spare), the total value is 20.

For a tenth frame of XXX (three strikes), the total value is 30.

## Requirements

Write code to keep track of the score of a game of bowling. It should support two operations:

• roll(pins : int) is called each time the player rolls a ball. The argument is the number of pins knocked down.
• score() : int is called only at the very end of the game. It returns the total score for that game.

For installation and learning resources, refer to the exercism help page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

gem install minitest

If you would like color output, you can require 'minitest/pride' in the test file, or note the alternative instruction, below, for running the test file.

Run the tests from the exercise directory using the following command:

ruby bowling_test.rb

To include color from the command line:

ruby -r minitest/pride bowling_test.rb

## Source

The Bowling Game Kata at but UncleBob http://butunclebob.com/ArticleS.UncleBob.TheBowlingGameKata

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### bowling_test.rb

require 'minitest/autorun'
require_relative 'bowling'

# Common test data version: 1.0.1 26e345e
class BowlingTest < Minitest::Test
def setup
@game = Game.new
end

def record(rolls)
rolls.each { |pins| @game.roll(pins) }
end

def test_should_be_able_to_score_a_game_with_all_zeros
# skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 0, @game.score
end

def test_should_be_able_to_score_a_game_with_no_strikes_or_spares
skip
record([3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6, 3, 6])
assert_equal 90, @game.score
end

def test_a_spare_followed_by_zeros_is_worth_ten_points
skip
record([6, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 10, @game.score
end

def test_points_scored_in_the_roll_after_a_spare_are_counted_twice
skip
record([6, 4, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 16, @game.score
end

def test_consecutive_spares_each_get_a_one_roll_bonus
skip
record([5, 5, 3, 7, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 31, @game.score
end

def test_a_spare_in_the_last_frame_gets_a_one_roll_bonus_that_is_counted_once
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 3, 7])
assert_equal 17, @game.score
end

def test_a_strike_earns_ten_points_in_a_frame_with_a_single_roll
skip
record([10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 10, @game.score
end

def test_points_scored_in_the_two_rolls_after_a_strike_are_counted_twice_as_a_bonus
skip
record([10, 5, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 26, @game.score
end

def test_consecutive_strikes_each_get_the_two_roll_bonus
skip
record([10, 10, 10, 5, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_equal 81, @game.score
end

def test_a_strike_in_the_last_frame_gets_a_two_roll_bonus_that_is_counted_once
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 7, 1])
assert_equal 18, @game.score
end

def test_rolling_a_spare_with_the_two_roll_bonus_does_not_get_a_bonus_roll
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 7, 3])
assert_equal 20, @game.score
end

def test_strikes_with_the_two_roll_bonus_do_not_get_bonus_rolls
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 10, 10])
assert_equal 30, @game.score
end

def test_a_strike_with_the_one_roll_bonus_after_a_spare_in_the_last_frame_does_not_get_a_bonus
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 3, 10])
assert_equal 20, @game.score
end

def test_all_strikes_is_a_perfect_game
skip
record([10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10])
assert_equal 300, @game.score
end

def test_rolls_cannot_score_negative_points
skip
record([])
assert_raises Game::BowlingError do
@game.roll(-1)
end
end

def test_a_roll_cannot_score_more_than_10_points
skip
record([])
assert_raises Game::BowlingError do
@game.roll(11)
end
end

def test_two_rolls_in_a_frame_cannot_score_more_than_10_points
skip
record([5])
assert_raises Game::BowlingError do
@game.roll(6)
end
end

def test_bonus_roll_after_a_strike_in_the_last_frame_cannot_score_more_than_10_points
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10])
assert_raises Game::BowlingError do
@game.roll(11)
end
end

def test_two_bonus_rolls_after_a_strike_in_the_last_frame_cannot_score_more_than_10_points
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 5])
assert_raises Game::BowlingError do
@game.roll(6)
end
end

def test_two_bonus_rolls_after_a_strike_in_the_last_frame_can_score_more_than_10_points_if_one_is_a_strike
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 10, 6])
assert_equal 26, @game.score
end

def test_the_second_bonus_rolls_after_a_strike_in_the_last_frame_cannot_be_a_strike_if_the_first_one_is_not_a_strike
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 6])
assert_raises Game::BowlingError do
@game.roll(10)
end
end

def test_second_bonus_roll_after_a_strike_in_the_last_frame_cannot_score_more_than_10_points
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 10])
assert_raises Game::BowlingError do
@game.roll(11)
end
end

def test_an_unstarted_game_cannot_be_scored
skip
record([])
assert_raises Game::BowlingError do
@game.score
end
end

def test_an_incomplete_game_cannot_be_scored
skip
record([0, 0])
assert_raises Game::BowlingError do
@game.score
end
end

skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
assert_raises Game::BowlingError do
@game.roll(0)
end
end

def test_bonus_rolls_for_a_strike_in_the_last_frame_must_be_rolled_before_score_can_be_calculated
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10])
assert_raises Game::BowlingError do
@game.score
end
end

def test_both_bonus_rolls_for_a_strike_in_the_last_frame_must_be_rolled_before_score_can_be_calculated
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 10])
assert_raises Game::BowlingError do
@game.score
end
end

def test_bonus_roll_for_a_spare_in_the_last_frame_must_be_rolled_before_score_can_be_calculated
skip
record([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 3])
assert_raises Game::BowlingError do
@game.score
end
end

# Problems in exercism evolve over time, as we find better ways to ask
# questions.
# The version number refers to the version of the problem you solved,
#
# Define a constant named VERSION inside of the top level BookKeeping
# module, which may be placed near the end of your file.
#
# In your file, it will look like this:
#
# module BookKeeping
#   VERSION = 1 # Where the version number matches the one in the test.
# end
#
# http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html
def test_bookkeeping
skip
assert_equal 3, BookKeeping::VERSION
end
end
# Game
class Game
attr_accessor :frames, :penultimate_roll, :last_roll
def initialize
@frames = []
@penultimate_roll = 0
@last_roll = 0
end

def roll(pins)
raise RuntimeError if invalid_pins?(pins)
if frames.any? && frames.last.second_throw.nil?
frames.last.second_throw = pins
else
frames << Frame.new(pins)
end
end

def score
frames.reduce(0) do |sum, frame|
sum + frame.score
end
end

def invalid_pins?(pins)
pins < 0 || pins > 10
end
end

class Frame
attr_accessor :first_throw, :second_throw
def initialize(first_throw, second_throw = nil, multiplier = 1)
@first_throw = first_throw
@second_throw = second_throw
@second_throw = 0 if strike?(first_throw)
@multiplier = multiplier
end

def score
first_throw + second_throw
end

def strike?(pins)
pins == 10
end
end