In Rails, how do you functional test a Javascript response format?

Question

If your controller action looks like this:

respond_to do |format|
  format.html { raise \'Unsupported\' }
  format.js # index.js.erb
end

and yo

Answer 1

These three seem to be equivalent:

1. get :index, :format => 'js'
2. @request.env['HTTP_ACCEPT'] = 'text/javascript'
3. @request.accept = "text/javascript"

They cause the controller to use a js template (e.g. index.js.erb)

Whereas simulating an XHR request (e.g. to get a HTML snippet) you can use this: @request.env['HTTP_X_REQUESTED_WITH'] = "XMLHttpRequest"

This means request.xhr? will return true.

Note that, when simulating XHR, I had to specify the expected format or I got an error:

get :index, format: "html"

Tested on Rails 3.0.3.

I got the latter from the Rails source, here: https://github.com/rails/rails/blob/6c8982fa137421eebdc55560d5ebd52703b65c65/actionpack/lib/action_dispatch/http/request.rb#L160