Integration testing with Authlogic?

For the life of me I don't understand why Authlogic isn't logging me in in this integration test. I haven't had any problems w/ Authlogic logging me in in functional tests using this code. According to the authlogic rdocs (http://tinyurl.com/mb2fp2), simulating a logged-in state is the same in functional & integration tests, so i'm pretty confused. any help is MUCH appreciated!

class TipsController < ApplicationController
  before_filter :require_user,  :only => [:destroy, :undelete]
  def destroy
    @tip = Tip.find(params[:id])

    if can_delete?(@tip)

      @tip.destroy

      set_flash("good", "Tip deleted. <a href=\"#{undelete_tip_url(@tip.id)}\">Undo?</a>")
      respond_to do |format|
        format.html { redirect_to city_path(@tip.city)} 
      end
    else
      set_flash("bad", "Seems like you can't delete this tip, sorry.")
      respond_to do |format|
        format.html { render :action => "show", :id => @tip} 
      end
    end
  end
end


class DeleteTipAndRender < ActionController::IntegrationTest
  context "log user in" do
    setup do
      @user = create_user
      @tip = create_tip
    end

    context "delete tip" do
      setup do
        activate_authlogic
        UserSession.create(@user)
        @us = UserSession.find
        post "/tips/destroy", :id => @tip.id
      end

      should_redirect_to("city_path(@tip.city)"){city_path(@tip.city)} 
    end
  end
end

Based on the code in the user_sessions_controller create method, which takes a hash of the login credentials, I was able to make it work like this in my integration test:

UserSession.create(:email => 'someone@example.com', :password => 'password')

but not with:

UserSession.create(@user)