How do I test a redirect in sinatra using rspec?

Question

I'm trying to test for a redirect on the homepage in my sinatra app (more specifically, a padrino app), in rspec. I've found redirect_to, however it seems to be in rspec-rails only. How do you test for it in sinatra?

So basically, I'd like something like this:

  it "Homepage should redirect to locations#index" do
    get "/"
    last_response.should be_redirect   # This works, but I want it to be more specific
    # last_response.should redirect_to('/locations') # Only works for rspec-rails
  end