Proof of concept trailing whitespace visualizer (idea by @jackiekircher)

whitespace.rb

module Whitespace
  def self.trollify path, code
    code.chomp!.gsub!(/([ \t]+)$/) do |match|
      "; Whitespace::annoy(#{match.length})"
    end

    code.gsub!(/\brequire_relative\s*\(?\s*(.+?)\s*\)?;?$/) do |match|
      "Whitespace::require_relative #{$1}, binding(), '#{path}'"
    end
    code
  end

  def self.require_relative s, b = binding(), path = ""
    s = File.expand_path(s, path)
    return if /\bwhitespace(?:.rb)?$/ =~ s

    eval trollify(File.dirname(s), File.open(s).read), b
  end

  def self.annoy(number_of_spaces)
    number_of_spaces.times do
      sleep(1)
    end
  end
end

caller_file = caller.first.split(/:\d/, 2).first

abs_path = File.expand_path(caller_file, File.dirname(caller_file))
Whitespace::require_relative abs_path, binding()

exit