Using the Asset Pipeline outside of Rails - Serving CoffeeScript and SASS

application.css.scss

h2 {
  font-size: 10em;
  a {
    height: 64px;
    width: 50px;
    display: block;
  }
}

application.js.coffee

$(document).ready ->
  $('#foo').html("<p>bar</p>")  

application2.js.coffee.erb

$(document).ready ->
  $('img').attr('src', "<%= asset_path('lolwut.png') %>")

Gemfile

source "http://rubygems.org"

gem 'sprockets', :git => 'git://github.com/sstephenson/sprockets.git'
gem 'coffee-script'
gem 'sass'
gem 'rack-test'
gem 'sinatra'

pipeline.rb

require 'bundler/setup'
Bundler.require

assets = Sprockets::Environment.new('/path/to/standalone-pipeline') do |env|
  env.logger = Logger.new(STDOUT)
end

assets.append_path('/path/to/standalone-pipeline/assets')

module AssetHelpers
  def asset_path(name)
    "/assets/#{name}"
  end
end

assets.context_class.instance_eval do
  include AssetHelpers
end

get '/assets/*' do
  new_env = env.clone
  new_env["PATH_INFO"].gsub!("/assets", "")
  assets.call(new_env)
end

session = Rack::Test::Session.new(Rack::MockSession.new(assets))
session.get('application.css')
puts session.last_response.body