Rspec test CSV file download

I want to make sure my CSV download contain the correct columns. When I test a CSV download with RSpec I cannot access the file contents. How do I access the contents of the CSV file?

require 'spec_helper'
include Devise::TestHelpers

describe Admin::ApplicationsController do

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

  it "downloads a csv"
  it "gives us only the columns we want" do
    get :index, format: :csv
    p response.body
    p response.headers
  end
end

The output of the test:

# This is the output in the terminal
# ""
# {"Content-Type"=>"text/csv; charset=utf-8", "Content-Disposition"=>"attachment; filename=\"applications-2013-12-17.csv\""}