Set requests' header inside spec/routing

I'm working on a Rails application having a REST API in JSON format and versioned (according to this excellent Ryan's cast: #350 REST API Versioning - RailsCasts).

For instance, there is a spec/requests spec:

  require 'spec_helper'

  describe "My Friends" do     describe "GET /my/friends.json" do       it "should get my_friends_path" do         get v1_my_friends_path, {}, {'HTTP_ACCEPT' => 'application/vnd.myapp+json; level=1'}         response.status.should be(401)       end     end   end

And it works well. But (keeping this example) how can we write the routing spec? For instance this spec isn't correct:

  require 'spec_helper'

  describe "friends routing" do     it "routes to #index" do       get("/my/friends.json", nil, {'HTTP_ACCEPT' => 'application/vnd.myapp+json; level=1'}).         should route_to({ action: "index",                       controller: "api/v1/private/my/friends",                           format: "json" })     end   end

...because `get` can take only 1 param.

I tried different ways (such as with request.headers['Accept'] or @request.headers['Accept']... where request is undefined and @request is nil). I really don't see how to do.

I'm on Ruby 1.9.3, Rails 3.2.6 and rspec-rails 2.11.0. Thanks.