Autotest by Ryan Davis (aka ZenSpider) is a sweet tool that ships with ZenTest whose job is to keep you informed of test or specification failure as you’re coding your app. Whenever your source files change it reruns the applicable tests and reports the results.

Autotest’s usefulness shines with its dead-simple mechanism for hooking into events such as “test failed” or “all tests passed,” and, as a result, ships with a bunch of useful prebuilt hooks: Autoupdate, Emacs, Fixtures, Growl, Heckle, HtmlReport, Menu, Migrate, Notify, Pretty, RedGreen, Screen, Shame, Snarl and Timestamp.

Configuring autotest is done by simply creating a .autotest file in your project root or home directory. It’s simply a Ruby file, without the .rb extension, defining your hooks or require’ing the ones that ship with ZenTest. ZenTest includes an example config, example_dot_autotest.rb, in the root directory of the ZenTest gem which I highly recommend checking out. Whilst you’re there, have a look inside lib/autotest for the various bits and bobs it ships with.

I’m currently ripping the guts out of legacy app that needs redeploying—yes, I’m adding specs whilst I’m there—so to make life easier for myself I created the following .autotest. I’ve added a custom version of AutoTest::Fixtures and AutoTest::RedGreen to better deal with RSpec’s eccentricities, and Autotest::Speak to speak out test failures via Applescript.

# Just like Autotest::Fixtures, but for specs
module Autotest::SpecFixtures
  Autotest.add_hook :initialize do |at|
    at.test_mappings['^spec/fixtures/(.*)s.yml'] = proc { |filename, matches|
      at.files_matching(/spec\/\w+\/#{matches[1]}(_\w+)?.*_spec.rb$/)
    }
  end
end

# Just like Autotest::RedGreen, but for specs
module Autotest::SpecRedGreen
  BAR = "=" * 80

  Autotest.add_hook :ran_command do |at|
    # TODO: submit a patch for RedGreen to make the match and code configurable
    if at.results.last.match(/^(\d+) examples?, (\d+) failures?$/)
      code = ($2 != "0") ? 31 : 32
      puts "\e[#{code}m#{BAR}\e[0m\n\n"
    end
  end
end

# Speak failures via Apple's speech synth
module Autotest::Speak
  def self.speak message
    system %(osascript -e 'say "#{message}"')
  end

  Autotest.add_hook :red do |at|
    failures = at.files_to_test.size
    speak "#{failures} example#{failures == 0 || failures > 1 ? 's' : nil} failed."
  end

  # Autotest.add_hook :green do |at|
  #   speak "Specs passed."
  # end

  Autotest.add_hook :all_good do |at|
    speak "All specs passed."
  end
end

The possibilities for customising autotest are endless: set up your own continuous integration using Autotest::AutoUpdate with remote-growl, IRC and email notifications; or, write something that uses uses Ruby/SerialPort to make your office’s talking moose head (you do have one, don’t you?) read haiku on behalf of the team member who comitted failing code.