Rails controller create action for Mongoid embedded_in model. What is the right way to test the post :create action in this situation?

gistfile1.rb

# app/models/user.rb
class User
  include Mongoid::Document
  embeds_many :api_applications
  ...
end

# app/models/api_application.rb
class ApiApplication
  include Mongoid::Document

  field :name,         :type => String
  field :main_url,     :type => String
  field :callback_url, :type => String
  embedded_in :user
  ...
end

# app/controllers/api_applications_controller.rb
class ApiApplicationsController < ApplicationController
  before_filter :authenticate_user!
  
  ...
  
  def create
    @api_application = current_user.api_applications.new(params[:api_application])

    respond_to do |format|
      if @api_application.save
        format.html { redirect_to @api_application, notice: 'Your application was successfully created.' }
      else
        format.html { render action: "new" }
      end
    end
  end
  
  ...
end

# spec/controllers/api_applications_controller_spec.rb
require 'spec_helper'

describe ApiApplicationsController do
  before (:each) do
    @user = FactoryGirl.create(:user)
    sign_in @user
  end
  
  let(:valid_attributes) { { name: "test app",
                             main_url: "http://localhost:8080",
                             callback_url: "http://localhost:8080" } }

  ...
  
  describe "POST create" do
    describe "with valid params" do
      it "creates a new ApiApplication" do
        expect {
          post :create, { :api_application => valid_attributes }
        }.to change(@user.api_applications, :count).by(1)
      end
    end
  end
end

# spec/factories/users.rb
FactoryGirl.define do
  factory :user do
    name 'Test User'
    email 'example@example.com'
    password 'mong01dtest'
    password_confirmation 'mong01dtest'
    confirmed_at Time.now
  end
end


# The spec fails with this error: 
# Failure/Error: expect {
#       count should have been changed by 1, but was changed by 0
       
# How can I test the post :create action in this situation?

The answer is to use reload because counts are cached.

expect {
  post :create, { :api_application => valid_attributes }
}.to change { @user.reload.api_applications.count }.by(1)