Simple solution, a rake task for use CoffeeScript in Jasmine. Supported: 1. write code in CoffeeScript 2. write spec in CoffeeScript. Could be used in any Ruby application (Sinatra, Rails ...)

Rakefile

require 'bundler/gem_tasks'
require 'jasmine'
require 'coffee-script'
require 'fileutils'

load 'jasmine/tasks/jasmine.rake'

task 'test' do
  pattern = '{**/*.rb,**/*.slim,**/*.coffee}'

  system %Q(bundle exec rerun --pattern '#{pattern}' -cx rake test_engine)
end

task 'test_engine' do
  system 'rspec'

  # lib *.coffee -> /spec/javascripts/cache
  # spec *.coffee -> /spec/javascripts/cache

  # put /spec/javascripts/cache in .gitignore

  # in jasmine.yml change
  # src_files:
  #   - spec/javascripts/cache/lib/**/*.js


  compile_coffee [ 'lib/redsi/views/js/**/*.coffee' ], '/spec/javascripts/cache/lib/scripts.js'
  compile_coffee [ 'spec/javascripts/**/*.coffee' ], '/spec/javascripts/cache/spec.js'

  system 'rake jasmine:ci'
end

private

def compile_coffee(dirs, target_file)
  def path(relative)
    root = File.dirname(__FILE__)
    File.join(root, relative)
  end

  target_file = path(target_file)

  dirs.each do |pattern|
    js = Dir.glob(path(pattern)).map do |coffee_file_path|
      CoffeeScript.compile(File.read(coffee_file_path))
    end.join(' ')

    FileUtils.mkdir_p(File.dirname(target_file))
    File.write(target_file, js)
  end
end