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nihilismus's solution

to Raindrops in the Ruby Track

Published at Aug 11 2020 · 0 comments
Instructions
Test suite
Solution

Convert a number to a string, the contents of which depend on the number's factors.

  • If the number has 3 as a factor, output 'Pling'.
  • If the number has 5 as a factor, output 'Plang'.
  • If the number has 7 as a factor, output 'Plong'.
  • If the number does not have 3, 5, or 7 as a factor, just pass the number's digits straight through.

Examples

  • 28's factors are 1, 2, 4, 7, 14, 28.
    • In raindrop-speak, this would be a simple "Plong".
  • 30's factors are 1, 2, 3, 5, 6, 10, 15, 30.
    • In raindrop-speak, this would be a "PlingPlang".
  • 34 has four factors: 1, 2, 17, and 34.
    • In raindrop-speak, this would be "34".

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 raindrops_test.rb

To include color from the command line:

ruby -r minitest/pride raindrops_test.rb

Source

A variation on a famous interview question intended to weed out potential candidates. http://jumpstartlab.com

Submitting Incomplete Solutions

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

raindrops_test.rb

require 'minitest/autorun'
require_relative 'raindrops'

# Common test data version: 1.1.0 99de15d
class RaindropsTest < Minitest::Test
  def test_the_sound_for_1_is_1
    # skip
    assert_equal "1", Raindrops.convert(1)
  end

  def test_the_sound_for_3_is_pling
    skip
    assert_equal "Pling", Raindrops.convert(3)
  end

  def test_the_sound_for_5_is_plang
    skip
    assert_equal "Plang", Raindrops.convert(5)
  end

  def test_the_sound_for_7_is_plong
    skip
    assert_equal "Plong", Raindrops.convert(7)
  end

  def test_the_sound_for_6_is_pling_as_it_has_a_factor_3
    skip
    assert_equal "Pling", Raindrops.convert(6)
  end

  def test_2_to_the_power_3_does_not_make_a_raindrop_sound_as_3_is_the_exponent_not_the_base
    skip
    assert_equal "8", Raindrops.convert(8)
  end

  def test_the_sound_for_9_is_pling_as_it_has_a_factor_3
    skip
    assert_equal "Pling", Raindrops.convert(9)
  end

  def test_the_sound_for_10_is_plang_as_it_has_a_factor_5
    skip
    assert_equal "Plang", Raindrops.convert(10)
  end

  def test_the_sound_for_14_is_plong_as_it_has_a_factor_of_7
    skip
    assert_equal "Plong", Raindrops.convert(14)
  end

  def test_the_sound_for_15_is_plingplang_as_it_has_factors_3_and_5
    skip
    assert_equal "PlingPlang", Raindrops.convert(15)
  end

  def test_the_sound_for_21_is_plingplong_as_it_has_factors_3_and_7
    skip
    assert_equal "PlingPlong", Raindrops.convert(21)
  end

  def test_the_sound_for_25_is_plang_as_it_has_a_factor_5
    skip
    assert_equal "Plang", Raindrops.convert(25)
  end

  def test_the_sound_for_27_is_pling_as_it_has_a_factor_3
    skip
    assert_equal "Pling", Raindrops.convert(27)
  end

  def test_the_sound_for_35_is_plangplong_as_it_has_factors_5_and_7
    skip
    assert_equal "PlangPlong", Raindrops.convert(35)
  end

  def test_the_sound_for_49_is_plong_as_it_has_a_factor_7
    skip
    assert_equal "Plong", Raindrops.convert(49)
  end

  def test_the_sound_for_52_is_52
    skip
    assert_equal "52", Raindrops.convert(52)
  end

  def test_the_sound_for_105_is_plingplangplong_as_it_has_factors_3_5_and_7
    skip
    assert_equal "PlingPlangPlong", Raindrops.convert(105)
  end

  def test_the_sound_for_3125_is_plang_as_it_has_a_factor_5
    skip
    assert_equal "Plang", Raindrops.convert(3125)
  end
end
# frozen_string_literal: true

# Based on: https://refactoring.guru/design-patterns/chain-of-responsibility/ruby/example

class Integer
  def factors()
    (1..self).select { |number| (self % number).zero? }
  end

  def factor?(number)
    number.factors.include? self
  end
end

class Handler
  def next_handler=(handler)
    raise NotImplementedError, "#{self.class} has not implemented method '#{__method__}'"
  end

  def handle(request)
    raise NotImplementedError, "#{self.class} has not implemented method '#{__method__}'"
  end
end

class AbstractHandler < Handler
  attr_writer :next_handler

  def next_handler(handler)
    @next_handler = handler
    handler
  end

  def handle(request)
    return @next_handler.handle(request) if @next_handler

    nil
  end
end

class Pling < AbstractHandler
  def handle(number)
    (3.factor?(number) ? 'Pling' : '') + super(number)
  end
end

class Plang < AbstractHandler
  def handle(number)
    (5.factor?(number) ? 'Plang' : '') + super(number)
  end
end

class Plong < AbstractHandler
  def handle(number)
    (7.factor?(number) ? 'Plong' : '') + super(number)
  end
end

class Plzng < AbstractHandler
  def handle(number)
    return number.to_s unless 3.factor?(number) || 5.factor?(number) || 7.factor?(number)

    ''
  end
end

class Raindrops
  def self.convert(number)
    pling = Pling.new
    plang = Plang.new
    plong = Plong.new
    plzng = Plzng.new

    pling.next_handler(plang).next_handler(plong).next_handler(plzng)
    pling.handle(number)
  end
end

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