it's not pretty, but it's mine

gistfile1.rb

%w[autotest/fsevent autotest/timestamp redgreen/autotest autotest/growl test_notifier/runner/autotest].each do |lib|
  begin
    require lib
  rescue LoadError => e
    warn "Couldn't load #{lib}: #{e}"
  end
end

TestNotifier.default_notifier = :growl if defined? TestNotifier

if defined? Autotest::Growl
  Autotest::Growl::clear_terminal = false

  # ~/Library/Autotest should inlcude failed.png, passed.png and pending.png
  growl_image_dir = File.join(ENV["HOME"], "Library", "Autotest")
  Autotest::Growl::image_dir = growl_image_dir if File.directory? growl_image_dir
end

# skip some paths
Autotest.add_hook :initialize do |autotest|
  %w[.git .svn .hg .swp .DS_Store ._* tmp db log tmp vendor rerun.txt Gemfile.lock].each do |exception|
    autotest.add_exception(exception)
  end

  # add mappings for files test files that end in 'test'
  autotest.add_mapping %r%^(test)/.*_test.rb$% do |filename, _|
    filename
  end

  autotest.add_mapping %r%^lib/(.*)\.rb$% do |_, match|
    ["test/#{match[1]}_test.rb"]
  end

  # option to use for unit_diff
  autotest.unit_diff = "cat"
end

class Autotest
  # don't rerun the entire suite when fixing broken specs
  def rerun_all_tests
  end
end

this is my ~/.autotest file