authenticated_test_helper.rb

module AuthenticatedTestHelper
  def login_as(role, opts={})
    user = users(role) if role.is_a?(Symbol) && self.respond_to(:users)
    user ||= create_user(role.to_s, opts)
    controller.send(:current_user=, user)
    # so we'll have access to it from the specs.. 
    @current_user = user
  end

  def authorize_as(user)
    request.env["HTTP_AUTHORIZATION"] = user ? "Basic #{Base64.encode64("#{users(user).login}:test")}" : nil
  end

  def create_user(user, opts={})
    options = {
      :name => "#{user.to_s.titleize} Jones", 
      :email => "#{user.to_s.downcase.gsub(/\W/,'_')}@example.com", 
      :phone => '2145551111',
      :role => mock_model(Role, :name => user, :to_s => user), 
      :dealer => nil,
      :active? => true,
      :password_required? => false
    }.merge(opts)
    mock_model(User, options)
  end
  
end

some_controller_spec.rb

describe SomeController do
  before(:each) do
    login as 'user'
  end
  ...
end

spec_helper.rb

Spec::Runner.configure do |config|
  config.inlcude AuthenticatedTestHelper
end