Testing nested rails route with :path => ''

In my routes.rb I have

resources :users, :path => '', param: :name do
  resources :locations
end

This gives me my URLs exactly like I want them, e.g. http://ift.tt/1Os1EFn

However, I just can't figure out, how to test them. I ran over this, but it doesn't seem to be enough.

setup do
  @location = locations(:one)
  @user = users(:one)
end

test "should get index" do
  get :index, user_id: @user.name
  assert_response :success
  assert_not_nil assigns(:locations)
end

Can someone point me into the right direction? Or is there a better (and testable) way, to achieve my URL-pattern?