how to use padrino helper methods in rspec
describe "POST /sessions" do
    it "should populate current_user after posting correct user/pass" do

      u = User.create({:email=>"john@gmail.com", :password=>"helloworld", :password_confirmation=>"helloworld"})

      user = {
        email:"john@gmail.com",
        password:"hellowolrd"
      }
      post '/sessions/new', user
      current_user.should_not == "null"
    end
  end

post "/new" do
    user = User.authenticate(params[:email], params[:password])
    if user
      session[:user_id] = user.id
      redirect '/'
    else
      render "sessions/new"
    end
  end

Testing.helpers do
  def current_user
    @current_user ||= User.find(:id=>session[:user_id]) if session[:user_id]
  end
end

Failures:

  1) SessionsController POST /users should populate current_user after posting correct user/pass
     Failure/Error: current_user.should_not == "null"
     NameError:
       undefined local variable or method `current_user' for #<RSpec::Core::ExampleGroup::Nested_1::Nested_2:0x0000000313c0d8>
     # ./spec/app/controllers/sessions_controller_spec.rb:20:in `block (3 levels) in <top (required)>'