Problem with Controller Testing using Devise

My first post on stackoverflow...Yeeh !. Anyways I'm trying to do a simple controller test for devise on Ruby 192 and Rails 3.0. I went through a lot of stuff on the web but I'm stuck. Please help me out. Here is the code snippet

require 'spec_helper'
require 'devise/test_helpers'

describe AttributeFunnel do
   include Devise::TestHelpers

  before(:each) do
    @request.env["devise.mapping"] = Devise.mappings[:admin]
  end

  it "should restrict access" do
    @user = Factory.build(:user, :email => "single@user.com",:password =>"abc123",:password_confirmation => "abc123" ,:agree_terms => 1)
    @user.save(:validate => false)
    @user.confirm!
    sign_in(@user)
  end
end

This is the error >>

NoMethodError: undefined method `request' for nil:NilClass
C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.4/lib/active_support/whiny_nil.rb:48:in `method_missing'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/devise-1.2.rc/lib/devise/test_helpers.rb:27:in `initialize'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/devise-1.2.rc/lib/devise/test_helpers.rb:67:in `new'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/devise-1.2.rc/lib/devise/test_helpers.rb:67:in `warden'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rspec-rails-2.5.0/lib/rs开发者_Go百科pec/rails/adapters.rb:11:in `block (2 levels) in setup'

I put the @request.env as a last resort. Still not working :(