nihilismus's solution to Isogram on the Ruby track

Instructions

Test suite

Solution

Determine if a word or phrase is an isogram.

An isogram (also known as a "nonpattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.

Examples of isograms:

lumberjacks
background
downstream
six-year-old

The word isograms, however, is not an isogram, because the s repeats.

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 isogram_test.rb

To include color from the command line:

ruby -r minitest/pride isogram_test.rb

Source

Wikipedia https://en.wikipedia.org/wiki/Isogram

Submitting Incomplete Solutions

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

isogram_test.rb

require 'minitest/autorun'
require_relative 'isogram'

# Common test data version: 1.7.0 74869e8
class IsogramTest < Minitest::Test
  def test_empty_string
    # skip
    input = ""
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_isogram_with_only_lower_case_characters
    skip
    input = "isogram"
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_word_with_one_duplicated_character
    skip
    input = "eleven"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_word_with_one_duplicated_character_from_the_end_of_the_alphabet
    skip
    input = "zzyzx"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_longest_reported_english_isogram
    skip
    input = "subdermatoglyphic"
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_word_with_duplicated_character_in_mixed_case
    skip
    input = "Alphabet"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_word_with_duplicated_character_in_mixed_case_lowercase_first
    skip
    input = "alphAbet"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_hypothetical_isogrammic_word_with_hyphen
    skip
    input = "thumbscrew-japingly"
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_hypothetical_word_with_duplicated_character_following_hyphen
    skip
    input = "thumbscrew-jappingly"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_isogram_with_duplicated_hyphen
    skip
    input = "six-year-old"
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_made_up_name_that_is_an_isogram
    skip
    input = "Emily Jung Schwartzkopf"
    assert Isogram.isogram?(input), "Expected true, '#{input}' is an isogram"
  end

  def test_duplicated_character_in_the_middle
    skip
    input = "accentor"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end

  def test_same_first_and_last_characters
    skip
    input = "angola"
    refute Isogram.isogram?(input), "Expected false, '#{input}' is not an isogram"
  end
end

# frozen_string_literal: true

class String
  ALPHABET = %w[a b c d e f g h i j k l m n o p q r s t u v w x y z].freeze

  def with_repeated_letter?
    characters = downcase.chars.to_a
    counts = ALPHABET.map { |character| characters.count character }
    counts.select { |count| count > 1 }.sum.positive?
  end
end

class Isogram
  def self.isogram?(string)
    !string.with_repeated_letter?
  end
end

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nihilismus's solution

to Isogram in the Ruby Track

Source

Submitting Incomplete Solutions

isogram_test.rb

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