Numeric extension to get Look-and-say sequence number implementation. Ruby > 2.4.0

look_and_say.rb

module SpecificNumeric
  refine Numeric do

    PRESET_ITERATIONS_COUNT = 5

    def look_and_say
      _deep_look_and_say(Array.new(1, self))
    end

    private

    def _deep_look_and_say(arr, iteration_num = 0)
      if iteration_num < PRESET_ITERATIONS_COUNT
        arr << say_it!(arr.last)
        arr = _deep_look_and_say(arr, iteration_num + 1)
      end

      arr
    end

    def say_it!(number)
      pronounced = ''
      lr_digits = number.digits.reverse
      lr_digits.each_with_index do |digit, index|
        next if index > 0 && lr_digits[index - 1] == digit

        counter = check_next_digit(lr_digits, digit, index)
        pronounced += "#{counter}#{digit}"
      end

      pronounced.to_i
    end

    def check_next_digit(digits, current_digit, index, counter = 1)
      counter = check_next_digit(digits, digits[index + 1], index + 1, counter + 1) if current_digit == digits[index + 1]

      counter
    end
  end
end

look_and_say_test.rb

require_relative "look_and_say"
require "test/unit"

class TestSpecificModule < Test::Unit::TestCase
 
  def test_main
    assert_equal([1, 11, 21, 1211, 111221], 1.look_and_say.each.take(5))
    assert_equal([10, 1110, 3110], 10.look_and_say.each.take(3))
  end
end