Installing an Configuring Autotest

gem update ZenTest
gem install autotest-rails
gem install autotest-growl
gem install autotest-fsevent

Install growlnotify if not already installed

.zshrc

# For autotest
export RSPEC=true autospec
export AUTOFEATURE=true autospec

.autotest file

require 'autotest/growl'
require 'autotest/fsevent'
require 'autotest/timestamp'

Autotest::Growl::show_modified_files = false
Autotest::Growl::clear_terminal = false
Autotest::Growl::one_notification_per_run = true
# Autotest::Growl::sticky_failure_notifications = true

Autotest.add_hook :initialize do |autotest|
  %w{.git .svn .hg .DS_Store ._* vendor}.each {|exception| autotest.add_exception(exception) }
  false
end

Resources:

http://www.viget.com/extend/how-why-to-run-autotest-on-your-mac/
http://ph7spot.com/musings/getting-started-with-autotest
http://github.com/svoop/autotest-growl
http://github.com/svoop/autotest-fsevent
http://wiki.github.com/dchelimsky/rspec/autotest-integration
http://wiki.github.com/aslakhellesoy/cucumber/autotest-integration