closest web safe color...v2

closest_web_safe.rb

WEB_SAFE_NUMBERS = [
  0,   # 00
  51,  # 33
  102, # 66
  153, # 99
  204, # cc
  255  # ff
]

def closest_web_safe_color(string)
  string.gsub!('#', '')
  string = double_chars_if_needed(string)

  output = string.downcase.scan(/.{2}/).inject("#") do |memo, chunk|
    base_ten = chunk.to_i(16)
    closest_web_safe = WEB_SAFE_NUMBERS.min_by { |num| (base_ten - num).abs }
    closest_web_safe_hex = closest_web_safe.to_s(16).ljust(2, '0')

    memo << closest_web_safe_hex
  end

  if string.upcase == string
    output.upcase
  else
    output
  end
end

def double_chars_if_needed(string)
  if string.length < 6
    string = string.chars.map do |char|
      char * 2
    end.join
  else
    string
  end
end

require 'minitest/autorun'

class TestMoveZeroes < Minitest::Test
  def test_it_works
    assert_equal '#993300', closest_web_safe_color('#ae3312')
    assert_equal '#993300', closest_web_safe_color('#993300')
    assert_equal '#cc3300', closest_web_safe_color('de3214')
    assert_equal '#CC0033', closest_web_safe_color('#D40123')
    assert_equal '#333333', closest_web_safe_color('#323')
  end
end