Speed up capybara specs by setting user session directly in the app. To have access to the rack session use https://github.com/railsware/rack_session_access.

devise_integration.rb

def fast_log_in
  user = Factory.create(:user)
  warden_key = User.serialize_into_session(user).unshift('User')
  page.set_rack_session(:'warden.user.user.key' => warden_key)

  user
end