What should I set Capybara.app to when testing a nodeJS application?

I've seen like a million of times:

If you are not using Rails...

require 'capybara/cucumber'
Capybara.app = MyRackApp

But if you want to test a node.js express v4 application what is "MyRackApp"?

Thanks for the response

Capybara.app is for testing a Rack app in-process. Your app isn't a Rack app, so you have to test it out of process. See "Calling remote servers" in the Capybara documentation. Briefly,

Capybara.current_driver = :poltergeist # or :selenium if you prefer slower tests ;)
Capybara.app_host = 'http://your.app'

And don't set Capybara.app.