[ruby][raindrops] complete raindrops

ruby/raindrops/README.md

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+# Raindrops
+
+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](http://exercism.io/languages/ruby/resources).
+
+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](http://jumpstartlab.com)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

ruby/raindrops/raindrops.rb

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+# frozen_string_literal: true
+
+class Raindrops
+  def self.convert(number)
+    new(number).speak
+  end
+
+  def speak
+    speak_words = words
+    if speak_words.empty?
+      number.to_s
+    else
+      speak_words.join
+    end
+  end
+
+  private
+
+  FACTORS = {
+    3 => 'Pling',
+    5 => 'Plang',
+    7 => 'Plong'
+  }.freeze
+
+  private_constant :FACTORS
+
+  attr_reader :number
+
+  def initialize(number)
+    @number = number
+  end
+
+  def factors
+    FACTORS.keys.filter { (number % _1).zero? }
+  end
+
+  def words
+    factors.map { FACTORS[_1] }
+  end
+end

ruby/raindrops/raindrops_test.rb

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+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
+    assert_equal "1", Raindrops.convert(1)
+  end
+
+  def test_the_sound_for_3_is_pling
+    assert_equal "Pling", Raindrops.convert(3)
+  end
+
+  def test_the_sound_for_5_is_plang
+    assert_equal "Plang", Raindrops.convert(5)
+  end
+
+  def test_the_sound_for_7_is_plong
+    assert_equal "Plong", Raindrops.convert(7)
+  end
+
+  def test_the_sound_for_6_is_pling_as_it_has_a_factor_3
+    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
+    assert_equal "8", Raindrops.convert(8)
+  end
+
+  def test_the_sound_for_9_is_pling_as_it_has_a_factor_3
+    assert_equal "Pling", Raindrops.convert(9)
+  end
+
+  def test_the_sound_for_10_is_plang_as_it_has_a_factor_5
+    assert_equal "Plang", Raindrops.convert(10)
+  end
+
+  def test_the_sound_for_14_is_plong_as_it_has_a_factor_of_7
+    assert_equal "Plong", Raindrops.convert(14)
+  end
+
+  def test_the_sound_for_15_is_plingplang_as_it_has_factors_3_and_5
+    assert_equal "PlingPlang", Raindrops.convert(15)
+  end
+
+  def test_the_sound_for_21_is_plingplong_as_it_has_factors_3_and_7
+    assert_equal "PlingPlong", Raindrops.convert(21)
+  end
+
+  def test_the_sound_for_25_is_plang_as_it_has_a_factor_5
+    assert_equal "Plang", Raindrops.convert(25)
+  end
+
+  def test_the_sound_for_27_is_pling_as_it_has_a_factor_3
+    assert_equal "Pling", Raindrops.convert(27)
+  end
+
+  def test_the_sound_for_35_is_plangplong_as_it_has_factors_5_and_7
+    assert_equal "PlangPlong", Raindrops.convert(35)
+  end
+
+  def test_the_sound_for_49_is_plong_as_it_has_a_factor_7
+    assert_equal "Plong", Raindrops.convert(49)
+  end
+
+  def test_the_sound_for_52_is_52
+    assert_equal "52", Raindrops.convert(52)
+  end
+
+  def test_the_sound_for_105_is_plingplangplong_as_it_has_factors_3_5_and_7
+    assert_equal "PlingPlangPlong", Raindrops.convert(105)
+  end
+
+  def test_the_sound_for_3125_is_plang_as_it_has_a_factor_5
+    assert_equal "Plang", Raindrops.convert(3125)
+  end
+end