This is a bare-minimum testem configuration file that will allow you to use testem with a rails project. You save it in the root directory of the project (at the same level as the Gemfile), and then you can navigate to the project and run testem. How it works: What this configuration does is precompile the assets before the tests are run using t…

testem.json

{
  "framework": "jasmine",
	"src_files": [
		"app/assets/javascripts/*.js",
		"spec/scripts/*.js"
	],
	"serve_files": [
		"public/assets/*.js",
		"spec/scripts/*.js"
	],
	"before_tests": "rake assets:precompile RAILS_ENV=development",
	"after_tests": "rm -rf public/assets/"
}

If precompiling your assets takes too much time you may use symbolic links: http://afurmanov.com/2013/08/20/testing-javascript-in-isolation-from-rails/