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to High Scores in the Ruby Track

Published at Dec 16 2018 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Manage a game player's High Score list.

Your task is to build a high-score component of the classic Frogger game, one of the highest selling and addictive games of all time, and a classic of the arcade era. Your task is to write methods that return the highest score from the list, the last added score, the three highest scores, and a report on the difference between the last and the highest scores.

In this exercise you're going to instantiate a class and add some instance methods. http://ruby-for-beginners.rubymonstas.org/writing_classes/initializers.html

A HighScore accepts an array with one or more numbers, each representing one 'game score'. The Array class can offer inspiration for working with arrays. https://ruby-doc.org/core-2.5.1/Array.html


For installation and learning resources, refer to the Ruby resources 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 high_scores_test.rb

To include color from the command line:

ruby -r minitest/pride high_scores_test.rb

Source

Tribute to the eighties' arcade game Frogger

Submitting Incomplete Solutions

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

high_scores_test.rb

require 'minitest/autorun'
require_relative 'high_scores'

# Common test data version: 2.0.0 7a386a2
class HighScoresTest < Minitest::Test
  def test_list_of_scores
    # skip
    scores = [30, 50, 20, 70]
    expected = [30, 50, 20, 70]
    assert_equal expected, HighScores.new(scores).scores
  end

  def test_latest_score
    skip
    scores = [100, 0, 90, 30]
    expected = 30
    assert_equal expected, HighScores.new(scores).latest
  end

  def test_personal_best
    skip
    scores = [40, 100, 70]
    expected = 100
    assert_equal expected, HighScores.new(scores).personal_best
  end

  def test_personal_top
    skip
    scores = [50, 30, 10]
    expected = [50, 30, 10]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_personal_top_highest_to_lowest
    skip
    scores = [20, 10, 30]
    expected = [30, 20, 10]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_personal_top_when_there_is_a_tie
    skip
    scores = [40, 20, 40, 30]
    expected = [40, 40, 30]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_personal_top_when_there_are_less_than_3
    skip
    scores = [30, 70]
    expected = [70, 30]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_personal_top_when_there_is_only_one
    skip
    scores = [40]
    expected = [40]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_personal_top_from_a_long_list
    skip
    scores = [10, 30, 90, 30, 100, 20, 10, 0, 30, 40, 40, 70, 70]
    expected = [100, 90, 70]
    assert_equal expected, HighScores.new(scores).personal_top
  end

  def test_message_for_new_personal_best
    skip
    scores = [20, 40, 0, 30, 70]
    expected = "Your latest score was 70. That's your personal best!"
    assert_equal expected, HighScores.new(scores).report
  end

  def test_message_when_latest_score_is_not_the_highest_score
    skip
    scores = [20, 100, 0, 30, 70]
    expected = "Your latest score was 70. That's 30 short of your personal best!"
    assert_equal expected, HighScores.new(scores).report
  end

  def test_message_for_repeated_personal_best
    skip
    scores = [20, 70, 50, 70, 30]
    expected = "Your latest score was 30. That's 40 short of your personal best!"
    assert_equal expected, HighScores.new(scores).report
  end
end
class HighScores
  attr_reader :scores

  def initialize(scores)
    @scores = scores
  end

  def latest
    @scores.last
  end

  def personal_best
    @scores.max
  end

  def personal_top
    @scores.max(3)
  end

  def report
    "Your latest score was #{latest}. #{report_complement}"
  end

  private

  def report_complement
    return  "That's your personal best!" if new_personal_best?
    "That's #{difference_from_personal_best_to_latest} short of your personal best!"
  end

  def new_personal_best?
    latest == personal_best
  end

  def difference_from_personal_best_to_latest
    personal_best - latest
  end
end

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