coderpad.rb

# coderpad test
# https://coderpad.io/
# click Try Sandbox
# choose Ruby
# paste:

# 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.

class Isogram
end

require 'minitest/autorun'

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

solution_example.rb

class Isogram
  class << self
    # @param phrase [String] a word or phrase
    # @return [Boolean] if a word or phrase is an isogram
    def isogram?(phrase)
      base = phrase.downcase.tr(' -', '')
      base.chars.count == base.chars.uniq.count
    end
  end
end