ruby - proverb

ruby/proverb/README.md

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+# Proverb
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb. For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content. No line of the output text should be a static, unchanging string; all should vary according to the input given.
+
+* * * *
+
+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 proverb_test.rb
+
+To include color from the command line:
+
+    ruby -r minitest/pride proverb_test.rb
+
+
+## Source
+
+Wikipedia [http://en.wikipedia.org/wiki/For_Want_of_a_Nail](http://en.wikipedia.org/wiki/For_Want_of_a_Nail)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

ruby/proverb/proverb.rb

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+# Proverb class
+class Proverb
+  def initialize(*args, qualifier: nil)
+    @inputs = args.to_a
+    @qualifier = "#{qualifier} " if qualifier
+  end
+
+  def to_s
+    lines.join("\n") + "And all for the want of a #{@qualifier}#{@inputs[0]}."
+  end
+
+  private
+
+  def lines
+    @inputs.map.with_index do |_, index|
+      next if index == @inputs.length - 1
+
+      "For want of a #{@inputs[index]} the #{@inputs[index + 1]} was lost."
+    end
+  end
+end

ruby/proverb/proverb_test.rb

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+require 'minitest/autorun'
+require_relative 'proverb'
+
+class ProverbTest < Minitest::Test
+  def test_a_single_consequence
+    proverb = Proverb.new('nail', 'shoe')
+    expected = "For want of a nail the shoe was lost.\n" \
+      'And all for the want of a nail.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_a_short_chain_of_consequences
+    # skip
+    proverb = Proverb.new('nail', 'shoe', 'horse')
+    expected = "For want of a nail the shoe was lost.\n" \
+      "For want of a shoe the horse was lost.\n" \
+      'And all for the want of a nail.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_a_longer_chain_of_consequences
+    # skip
+    proverb = Proverb.new('nail', 'shoe', 'horse', 'rider')
+    expected = "For want of a nail the shoe was lost.\n" \
+      "For want of a shoe the horse was lost.\n" \
+      "For want of a horse the rider was lost.\n" \
+      'And all for the want of a nail.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_proverb_does_not_hard_code_the_rhyme_dictionary
+    #skip
+    proverb = Proverb.new('key', 'value')
+    expected = "For want of a key the value was lost.\n" \
+      'And all for the want of a key.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_the_whole_proverb
+    # skip
+    chain = %w(nail shoe horse rider message battle kingdom)
+    proverb = Proverb.new(*chain)
+    expected = "For want of a nail the shoe was lost.\n" \
+      "For want of a shoe the horse was lost.\n" \
+      "For want of a horse the rider was lost.\n" \
+      "For want of a rider the message was lost.\n" \
+      "For want of a message the battle was lost.\n" \
+      "For want of a battle the kingdom was lost.\n" \
+      'And all for the want of a nail.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_an_optional_qualifier_in_the_final_consequence
+    # skip
+    chain = %w(nail shoe horse rider message battle kingdom)
+    proverb = Proverb.new(*chain, qualifier: 'horseshoe')
+    expected = "For want of a nail the shoe was lost.\n" \
+      "For want of a shoe the horse was lost.\n" \
+      "For want of a horse the rider was lost.\n" \
+      "For want of a rider the message was lost.\n" \
+      "For want of a message the battle was lost.\n" \
+      "For want of a battle the kingdom was lost.\n" \
+      'And all for the want of a horseshoe nail.'
+    assert_equal expected, proverb.to_s
+  end
+
+  def test_proverb_is_same_each_time
+    # skip
+    proverb = Proverb.new('nail', 'shoe')
+    assert_equal proverb.to_s, proverb.to_s
+  end
+end