Rails: how to test and access custom routing

so far in routes.rb

match 'campaigns_mobile_application', to: 'campaigns#update_mobile_store_application', via: [:post, :get]

in spec_helper.rb

config.include Rails.application.routes.url_helpers

in controller_spec.rb

get campaigns_mobile_application_path format: :json # and here I have error

ok, I have error:

ActionController::RoutingError No route matches {:controller=>"campaigns", :action=>"/api/campaigns_mobile_application.json"}

change routes.rb now:

resources :campaigns do
  match 'mobile_application', to: 'campaigns#update_mobile_store_application', via: [:post, :get]
end

and also spec:

get campaign_mobile_application_path campaign_id: @campaign.id, format: :json

and again I catch error:

ActionController::RoutingError:
   No route matches {:controller=>"campaigns", :action=>"/api/campaigns/6775/mobile_application.json"}

How to fix this?