Testing nested resource controller with rspec in Rails 3.1 - ruby-on-rails

Question

I am trying to make a test for a controller for a nested resource.
The nesting is like this in the routes.rb
resources :cars, :only => [:index, :destroy, :show] do
resources :car_subscriptions, :only => [:new, :create], :as => :follow_subscriptions
end
I'm trying to test the create action most specifically:
describe CarSubscriptionsController do
def valid_attributes
{:car_id => '1', :user_id => '2'}
end
describe "POST create" do
describe "with valid params" do
it "creates a new CarSubscription" do
expect {
post :create, :car_id => 1, :car_subscription => valid_attributes
}.to change(CarSubscription, :count).by(1)
end
it "assigns a newly created car_subscription as #car_subscription" do
post :create, :car_subscription => valid_attributes
assigns(:car_subscription).should be_a(CarSubscription)
assigns(:car_subscription).should be_persisted
end
it "redirects to the created car_subscription" do
post :create, :car_subscription => valid_attributes
response.should redirect_to(CarSubscription.last)
end
end
end
end
It's actually a part of the scaffold generated by rails script. And I only modified the valid_attributes and the post in the first 'it'
And the output is this:
1) CarSubscriptionsController POST create with valid params creates a new CarSubscription
Failure/Error: post :create, :car_id => 1, :car_subscription => valid_attributes
ActionController::RoutingError:
No route matches {:car_id=>"1", :car_subscription=>{:car_id=>"1", :user_id=>"2"}, :controller=>"car_subscriptions", :action=>"create"}
# ./spec/controllers/car_subscriptions_controller_spec.rb:34:in `block (5 levels) in <top (required)>'
# ./spec/controllers/car_subscriptions_controller_spec.rb:33:in `block (4 levels) in <top (required)>'
It's the same error for all 'it's.
I've tried removing the :as => :following_subscriptions from the routes.rb file but the same problem.
I have actually split up the resources of car_subscriptions so index and destroy are in not nested, and create and new are nested in :cars
I don't want to use hard coded paths like in this answer but if it is the only way, I can give it a try:
{ :post => "/forum_topics/1/forum_sub_topics" }.should route_to(:controller => "forum_sub_topics", :action => "create", :forum_topic_id => 1)
EDIT
Oh, and my rake routes looks like this:
car_follow_subscriptions_da POST /biler/:car_id/car_subscriptions(.:format) {:action=>"create", :controller=>"car_subscriptions", :locale=>"da"}

Answer 1

From what rake routes provides, I guess you should replace:
post :create, :car_id => 1, :car_subscription => valid_attributes
with:
post :create, :car_id => 1, :car_subscription => valid_attributes, :locale => "da"