RailsTutorial Sign In flash not working

Question

I am trying to get the error flash to appear in the railstutorial.org sample app. So far this is what I have done. Can anyone help me find the error:

My RSPEC test fail:

1) SessionsController POST 'create' invalid signin should have a flash.now message
Failure/Error: flash.now[:error].should =~ /invalid/i
expected: /invalid/i
     got: nil (using =~)
./spec/controllers/sessions_controller_spec.rb:27

Controller code:

def create
  user = User.authenticate(params[:session][:email],
  params[:session][:password])
  if user.nil?
    flash.now[:error] = "Invalid email/password combination."
    @title = "Sign in"
    render 'new'
  else
    # Sign the user in and redirect to the user's show page.
  end
end

Test code:

describe "POST 'create'" do

describe "invalid signin" do

  before(:each) do
    @attr = { :email => "example@gmail.com", :password => "invalid"}
  end 

  it "should re-render the new page" do
    post :create, :session => @attr
    response.should render_template('new')
  end 
  it "should have a flash.now message" do
    post :create, :session => @attr
    flash.now[:error].should =~ /invalid/i
  end 
end