My Ruby string unindenter method

string_unindenter.rb

# encoding: utf-8

module StringUtils
  # Unindents a multiline string,
  # even if the first line is not the one with the least whitespace.
  # Best used with heredocs like this: <<-EOS.unindent ...
  # Note that if there are lines that are just newlines that
  # those will not break the next minimum indent length due to (?!\n) in the regex.
  # This is to get around editors which auto strip trailing whitespace on lines.
  # Otherwise any stripped whitespace on a blank line would kill the unindenting.
  # Test coverage in string_utils_test.rb
  def unindent
    gsub(/^#{scan(/^(?!\n)\s*/).min_by{|l|l.length}}/u, "")
  end
end

class String
  include StringUtils
end

########################### string_utils_test.rb
# encoding: utf-8

begin
  require 'test_helper'
rescue LoadError
  require File.expand_path(File.dirname(__FILE__) + '/../../test_helper')
end

class StringUtilsTest < ActiveSupport::TestCase
  context "with a heredoc that includes foreign characters" do
    setup do

    end

    should "not break extra indentation or encoding" do
      sample = <<-EOS.unindent
        This test
         is sponsored by
      Mötley Crüe

      EOS

      assert_equal "  This test\n   is sponsored by\nMötley Crüe\n\n", sample
    end

    should "be tolerant of editors that strip indented whitespace on a blank line and still unindent" do
      sample = <<-EOS.unindent
      This is the first line
       This is the second line

       This is the third line after a blank line
      EOS

      assert_equal "This is the first line\n This is the second line\n\n This is the third line after a blank line\n", sample
    end
  end
end