user_spec.rb

    describe 'it should regenerate the guid if one already exists' do
      FactoryGirl.create(:user, guid: '123456')
      SecureRandom.stub(:hex).and_return('123456', '456789')
      user = User.new(email: 'john@email.com', total_budget: 250.00)
      user.save
      expect(user.reload.guid).to eq(6)
    end