如何连接表的测试能力？

请帮忙解决问题 . 我使用gem'cancan'并将表连接到角色层次结构 . 模式：

create_table "roles", force: :cascade do |t|
  t.string   "name",       limit: 255
end

create_table "roles_users", id: false, force: :cascade do |t|
  t.integer "role_id", limit: 4
  t.integer "user_id", limit: 4
end

create_table "users", force: :cascade do |t|
  t.string   "email",                  limit: 255, default: "", null: false
  t.string   "encrypted_password",     limit: 255, default: "", null: false
end

我有3个角色：表角色：

id        name
0         user
1         manager
2         admin

我创建了3个用户，我给了他们角色：table roles_users：

role_id         user_id
2               2
1               3
0               1

ability.rb：

class Ability
  include CanCan::Ability
  def initialize(user)
    user ||= User.new # guest user (not logged in)

    if user.role? :admin
      can :manage, :all
      cannot :update, Review
    elsif user.role? :manager
      can :read, Review
      can :create, Review
      can :update, Review
      cannot :delete, Review
    elsif user.role? :user
      can :read, Review
      can :create, Review      
      cannot :update, Review
      cannot :delete, Review
    else
      can :read, Review
      cannot :create, Review
      cannot :update, Review
      cannot :delete, Review
    end   
  end   
end

厂：

FactoryGirl.define do
  factory :user do
    sequence(:email){ |i| "us#{i}@ad.ad" }
    password 'qwertyui'
    password_confirmation{ |u| u.password }    
  end 
end

FactoryGirl.define do
  factory :admin_status, class: Role do
    role_id 2
    user_id 2
  end

  factory :manager_status, class: Role do
    role_id 1
    user_id 3
  end

  factory :user_status, class: Role do
    role_id 0
    user_id 1
  end

end

我需要通过r规范管理员用户的测试能力：

require 'rails_helper'

RSpec.describe Review, type: :model do
  before(:each) do
    @user = FactoryGirl.create(:user) #create admin
    @ability = Ability.new(@user)
  end

  it "cannot delete review" do
    expect(@ability).to be_able_to(:delete, Review)
  end  
end

但运行测试控制台后显示如下错误信息：

kalinin@kalinin ~/rails/admin_book $ rspec spec/models/review_spec.rb
F
Failures:
  1) Review cannot delete review
     Failure/Error: expect(@ability).to be_able_to(:delete, Review)
       expected to be able to delete Review
     # ./spec/models/review_spec.rb:11:in `block (2 levels) in <top (required)>'

请帮助检查管理员用户的权限删除审核