Rspec json测试结果的日期格式错误

我试着测试我正在开发的Api。我也得到了正确的回答,但是日期格式似乎已经改变了

2018-11-27 18:03:44.000000000 +0000

到 2018-11-27T18:03:44.000Z

expected: [{"created_at"=>2018-11-27 18:03:44.000000000 +0000, "email"=>"jennettesaway...UfR7oeVa5.ZaWXce2qtn6Em2oSQuH6Iljqhx61BI7cvE3CG", "updated_at"=>2018-11-27 18:03:44.000000000 +0000}]

got: [{"created_at"=>"2018-11-27T18:03:44.000Z", "email"=>"georgene@champlin.biz...4$JlzdvIUfR7oeVa5.ZaWXce2qtn6Em2oSQuH6Iljqhx61BI7cvE3CG", "updated_at"=>"2018-11-27T18:03:44.000Z"}]

RSpec.describe UsersController, type: :request do

   let!(:user) { Fabricate(:user) }
   let(:valid_attributes) { Fabricate.attributes_for :user }
   let(:invalid_attributes) { Fabricate.attributes_for :invalid_user }
    # set headers for authorization
   #let(:headers) { { 'Authorization' => token_generator(user.id) } }
   let(:headers) { valid_headers }

   describe "GET #index" do
    before(:each) do
      #allow(request).to receive(:headers).and_return(headers)
    end

    it "returns a success response" do
      get "/users", params: {}, headers: valid_headers
      expect(json).to eq [user.as_json]
    end
   end
end

那是我的控制器

class UsersController < ApplicationController
  skip_before_action :authorize_request, only: :create
  before_action :set_user, only: [:show, :update, :destroy]

  # GET /users
  # GET /users.json
  def index
    @users = User.all
    render json: @users
  end
end

json

def json
  JSON.parse(response.body)
end