Rspec创建操作：预期#count已更改为1，但已更改为0

Question

我在我的应用上做了一些控制器测试，当我测试用于创建新服务的创建操作时，它给了我这个错误：＆＃34;预期#count已经改变了1，但是改为0＆＃34;

Theres my spec：

  before do
    @user = FactoryGirl.create(:user)
    sign_in @user
  end

  describe "POST #create" do
    context "with valid params" do
      it "creates a new Service" do
        expect {
          post :create, params: { user_id: @user, service: FactoryGirl.attributes_for(:service) }
        }.to change(Service, :count).by(1)
      end
    end
  end

我的工厂：

FactoryGirl.define do
  factory :service do
    name "Service Test"
    price 1
    time 15
    quantity 2
    user
  end
end

我的模特：

class Service
  include Mongoid::Document
  embedded_in :user
  field :name, type: String
  field :price, type: Float
  field :time, type: Integer
  field :quantity, type: Integer

  validates :name, :price, :time, :quantity, presence: true
end

控制器：

  def create
    @service = Service.new(service_params)
    @service.user = current_user
      if @service.save
        redirect_to services_path
      else
        redirect_to "/services"
      end
  end

错误：

 Failure/Error:
   expect {
     post :create, params: { user_id: @user, service: FactoryGirl.attributes_for(:service) }
   }.to change(Service, :count).by(1)

   expected #count to have changed by 1, but was changed by 0

我正在使用mongoid，顺便说一句。服务嵌入在用户中。