directories_to_watch

# File activesupport/lib/active_support/evented_file_update_checker.rb, line 174
      def directories_to_watch
        dtw = @dirs.keys | @files.map(&:dirname)
        accounted_for = dtw.to_set + Gem.path.map { |path| Pathname(path) }
        dtw.reject { |dir| dir.ascend.drop(1).any? { |parent| accounted_for.include?(parent) } }
      end