accounts_controller_spec.rb

describe AccountsController do
  before(:each) do
    login_user
  end

devise_spec_helper.rb

  module SpecHelpers

    def login_user(user = nil)
      @request.env["devise.mapping"] = Devise.mappings[:user]
      @user ||= Fabricate(:user)
      @user.confirm!
      sign_in @user
    end

  end