gistfile1.rb

# config/routes.rb
MyApp::Application.routes.draw do 
  resources :users
end

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def new
  end
end

# spec/controllers/users_controller_spec.rb
require 'spec_helper'

describe UsersController do
  it "should render a user registration page" do
    session[:redirect_to] = users_path
    get :new
    response.should be_success
  end
end

# => should render a user registration page
# =>   No route matches {:relative_url_root=>nil, :action=>"new"}