Test Feedzirra w/VCR using an HTTP proxy

.gitignore

cassettes

test.rb

#!/usr/bin/env ruby -Ku

# encoding: utf-8

# = Usage
#
# $ rspec test.rb

require 'io/wait'
require 'webrick'
require 'webrick/httpproxy'

require 'rubygems'
require 'active_support/deprecation'  # for feedzirra
require 'feedzirra'
require 'rspec'
require 'vcr'

module WEBrick
  class VCRProxyServer < HTTPProxyServer
    def service(*args)
      VCR.use_cassette('proxied') { super(*args) }
    end
  end
end

VCR.config do |config|
  config.stub_with :fakeweb
  config.cassette_library_dir = 'cassettes'
  config.default_cassette_options = { :record => :new_episodes }
end

describe 'A test with vcr and a transparent proxy' do
  IP   = '127.0.0.1'
  PORT = 9000

  before :all do
    reader, writer = IO.pipe

    @pid = fork do
      reader.close
      $stderr = writer
      server = WEBrick::VCRProxyServer.new(:BindAddress => IP, :Port => PORT)
      trap('INT') { server.shutdown }
      server.start
    end

    raise 'VCR Proxy did not start in 10 seconds' unless reader.wait(10)
  end

  after :all do
    Process.kill('INT', @pid)
  end

  it 'proxies to an RSS feed' do
    feed = Feedzirra::Feed.fetch_and_parse(
      'http://blog.wildfireapp.com/?feed=rss2',
      :proxy_url  => IP,
      :proxy_port => PORT
    )

    feed.should be_instance_of(Feedzirra::Parser::RSS)
  end
end

This approach is needed because Feedzirra is based on Curb::Multi, which is not currently supported by Feedzirra.

I looked at two other approaches, replacing Feedzirra in the application I maintain (but did not write), or changing it to use a different HTTP library. In both cases the amount of effort it would take seemed to be much greater than the benefits, so I settled on using a proxy until that code is rewritten at some point in the future.

This is pretty cool. I've setup VCR in a local proxy server before so that I can test HTTP requests from other languages (e.g. JS tests in Jasmine) and it worked quite nicely.

FWIW, VCR includes a rack middleware to make this pretty easy. That said, the Webrick approach you've done here looks even simpler. I don't know Webrick really at all (besides using it to boot rack apps) so I wasn't aware it had a built-in-proxy server. I've also been thinking of making a vcr-proxy-server gem that would make this even easier, and seeing your Webrick approach makes me think I may use Webrick instead of Rack like I was planning :).

One other thought: do you have other tests that use this VCR proxy setup besides the one here? Given the fact that you're only asserting that it is an instance of Feedzirra::Parser::RSS, and not actually making any assertion about what gets parsed out of the feed...it seems a bit like overkill to use VCR. Something simpler may do the trick.

@myronmarston: Oh, this was a code spike. The real tests this was written for include over a hundred tests that currently stub out Feedzirra. I was hoping to replace all that code with "real" calls to the backend services and use vcr to record/playback the requests.

I also did use the VCR rack middleware originally. In the git commit history I have a mostly fully functional HTTP proxy built on top of Net::HTTP and the middleware, but once I found out that WEBrick included it's own Net::HTTP based proxy I figured this was a nice way to cut out 50-60 loc. WEBRick's also included support for edge cases, as well as CONNECT support. Oddly enough though it does not include support for proxying PUT/DELETE, although those would be pretty easy to add if needed.

thx, very helpful!