deborah.rb

require 'rubygems'
require 'sinatra'
require 'haml'

$LOAD_PATH.unshift(File.dirname(__FILE__) + '/lib')
require 'oauth.rb'

enable :sessions

get '/' do
  if authenticated?
    redirect '/contacts'
  else
    haml :index
  end
end

def authenticated?
  !session[:authentication].nil?
end

deborah_spec.rb

require File.dirname(__FILE__) + '/spec_helper'

describe "Deborah" do
  include Rack::Test::Methods

  def app
    @app ||= Sinatra::Application
  end

  describe 'home page' do
    context 'when not authenticated' do
      it 'renders the page' do
        get '/'
        last_response.should be_ok
      end
    end

    context 'when authenticated' do
      it 'redirects to the contacts page' do
        app.stub!(:authenticated? => true) # DOES NOT WORK??!!
        get '/'
        last_response.should be_redirect
      end
    end
  end
end