How can I test my controller via rspec for something other than response.should be_success?

1) Right now this is just testing a successful response. However, since I've gone and created a Post via FactoryGirl... how can I test the @post.id equals one of the id's being returned by the get: index json?

    describe Api::V1::PostsController do

  context 'Post' do     before(:each) do       @post = FactoryGirl.create(:post)     end

    context '#index' do       it "should have a successful response on get index" do         get :index, format: :json         response.should be_success       end     end

EDIT:

2) How can I use "post :create" when my route is nested.

For example... this works great as an rspec controller post :create with a top level resource, such as post

      it "should get a success response on post create" do         post :create, params         response.should be_success       end

however, for a nested resource like 'comment' which is nested under post... the above would throw the following...

    Failure/Error: post :create, params      ActionController::UrlGenerationError:        No route matches

and if I tried

          it "should get a success response on post create" do         post :create, post_id: @post.id, params #@post is defined and created above         response.should be_success       end

I get this odd error...

    syntax error, unexpected '\n', expecting => (SyntaxError)

See this blog