Mixpanel test service

Logs all events sent to Mixpanel, if you replace the URL of the mixpanel API with the URL of this service.

  require "mixpanel_test/service"

  test_service = MixpanelTestService.new(:port => 3001)

  // The main purpose:
  // Post some stuff
  MixpanelTestService.transaction do // This gives you thread safe access to test_service
    test_service.events is a normal array containing all submitted events.
  end

  test_service.stop

  // Make the Mixpanel JS API post to this service instead of api.mixpanel.com
$ curl localhost:3001/libs/mixpanel-2.0.min.js # Or any other file in /libs

mixpanel_test_service proxies the js file from Mixpanel, caches it locally, and edits the mixpanel API url. The mixpanel API hostname gets replaced by localhost:3001 or whatever port we are running on, so if the script is run on a webpage, then all the Mixpanel API calls go to this service instead. All you have to do is load the script from the running mixpanel_test_service instead of the Mixpanel CDN. Use the same path

This gem proxies the mixpanel JS API file, but it does not distribute it. You will need internet to run your tests.

Sometimes, this gem gives me the following errors which come from net-http-server itself.

[Wed Sep 12 20:22:08 2012] /home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:98:in `write'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:98:in `block (2 levels) in write_headers'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:97:in `each_line'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:97:in `block in write_headers'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:94:in `each'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:94:in `write_headers'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/responses.rb:166:in `write_response'
/home/john/.rvm/gems/ruby-1.9.2-p290/gems/net-http-server-0.2.2/lib/net/http/server/daemon.rb:124:in `serve'
/home/john/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/gserver.rb:211:in `block (2 levels) in start'

It appears these errors are caused by the connection being closed before mixpanel_test_service has finished its response. For instance, this might be caused by instrumenting a submit button without delaying the form submit. The page will change, canceling the AJAX halfway through, and causing