When setting up a basic rails 3 application it seems like rspec-rails is unable to test nested routes. I've included a basic setup that should enable anyone to reproduce the error. This is present on both 2.1.0 and on master. One quick work around is to create a route directly to the controller.

routes.rb :

Testrspec2::Application.routes.draw do
  resources :two do
    resources :one
  end
end

one_controller_spec.rb :

require 'spec_helper'

describe OneController do
  it "should be successful" do
    get "index"
    response.should be_success
  end
end

one_controller.rb :

class OneController < ApplicationController
end