You can use carrot with celerity, or another driver.

1. gem 'rails-carrot', :require => 'carrot'

2. add a celerity_helper
/spec/celerity_helper.rb

3. Add some code in celerity_helper
require 'database_cleaner' 
require 'celerity' # You can change driver
require 'carrot'

ENV["RAILS_ENV"] = 'celerity' # You can change it with your environment
require File.expand_path("../../config/environment", __FILE__)
require 'rspec/rails'



4. Three test styles

If you don't use JRuby, you just can use Remote and Local.

a) Remote
Carrot.configure do |config|
  config.run_server = false
  config.app_host = "www.google.com"
end
Carrot.register_driver(Celerity::Browser.new)

b) Local
Carrot.configure do |config|
  config.run_server = true
end
Carrot.register_driver(Celerity::Browser.new)

c) Local, server with external ruby, You should use jruby to run RSpec.

Carrot.configure do |config|
  config.run_server = true
  config.external_ruby = true
  config.rails_command = "~/.rvm/gems/ruby-1.9.2-p0/bin/rails s -e celerity -p 3001"
  config.project_path = "#{Rails.root}"
  config.server_port = 3001
  # config.server_debug = true
end
Carrot.register_driver(Celerity::Browser.new)

RSpec.configure do |config|
   DatabaseCleaner.strategy = :truncation 
  
   config.before :each do 
     @browser = Carrot.driver   # get native driver
     DatabaseCleaner.clean 
   end

   config.after :all do
     DatabaseCleaner.clean 
   end
 
   config.use_transactional_fixtures = false

end

5 Test
a) get url
Carrot.url(path)
eg:
Carrot.url('/')        =>   http://host/
Carrot.url('/hello')   =>   http://host/hello

b) get native browser driver
Carrot.driver

6 FAQ
a) Does Carrot support server with external ruby?
Yes, but it just supports jruby run rspec and run server using external ruby. I use jruby to create native java process to run server using external ruby.

If you want to use ruby to run rspec and run server using external ruby, you can create a new server class to support it or wait for my upgrade.