Cool Enumerable#each_with_progress I once wrote so I can see how long iterating will take. I have waited too long on empty processes already. Most of the code is a blatant copy of existing code I found on the interwebs, but unfortunately I don't remember where. My contributions are mostly with the RAILS_ENV guard and the output.

each_with_progress.rb

module Enumerable
  def each_with_progress(&block)
    if ENV['RAILS_ENV'] == 'test'
      each do |element|
        block.call element
      end
    else
      out   = $stderr
      time  = Time.current
      total = count
      pretext = "> starting @ #{time.strftime('%H:%M')} -- processing #{total} items..."
      each_with_index do |element, i|
        out.print enumerating_line(i + 1, total, time)
        block.call element
      end
      end_time = Time.current
      duration = ((end_time - time) / 60).round(1)
      duration_unit = duration > 1 ? "minutes" : "seconds"
      out.print "\r< started @ #{time.strftime('%H:%M')} -- processed #{total} items in #{duration} #{duration_unit}\n"
    end
    self
  end

  protected

  def enumerating_progress_spinner
    @enumerating_progress_spinner ||= Enumerator.new do |e|
      loop do
        e.yield '|'
        e.yield '/'
        e.yield '-'
        e.yield '\\'
      end
    end
  end

  def enumerating_line(increment, total, time)
    percentage  = (increment * 100.0) / total
    difference  = (total * (Time.current - time)) / increment
    pretext     = ["\r> started @ ", time.strftime("%H:%M"), " -- processing #{total} items ", '[ETA: ', (time + difference).strftime("%H:%M"), '] '].join
    posttext    = format("[%5.1f%%]", percentage)
    progress    = ((percentage / 100.0) * (Integer((`tput cols` || '80').chomp) - pretext.length - posttext.length - 2)).ceil.times.map {}.join('=')
    spinner     = percentage >= 100 ? " " : enumerating_progress_spinner.next
    [pretext, progress, spinner, posttext].join(" ")
  end
end