Experiment Driven Development for Ruby
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Vanity is an Experiment Driven Development framework for Rails.

A/B Testing With Rails (In 5 Easy Steps)

Step 1: Start using Vanity in your Rails application:

== Rails 2.x configuration

Rails::Initializer.run do |config|
  gem.config "vanity"

  config.after_initialize do
    require "vanity"

== Rails 3 configuration

gem 'vanity' # in Gemfile, either outside of a group or inside of a bundler group


class ApplicationController < ActionController::Base
  use_vanity :current_user

Step 2: Define your first A/B test. This experiment goes in the file experiments/price_options.rb:

ab_test "Price options" do
  description "Mirror, mirror on the wall, who's the better price of all?"
  alternatives 19, 25, 29
  metrics :signups

NOTE: If using a metric as above ("signups"), there needs to be a corresponding ruby file for that metric. Inside the "experiments" directory create a "metrics" directory with a file called "signup.rb". The contents of the file can describe the signup metric, refer to the "Metrics" Vanity documentation page for an example.

Step 3: Present the different options to your users:

<h2>Get started for only $<%= ab_test :price_options %> a month!</h2>

Step 4: Measure conversion:

class SignupController < ApplicationController
  def signup
    @account = Account.new(params[:account])
    if @account.save
      track! :signups
      redirect_to @acccount
      render action: :offer

Step 5: Check the report:

vanity report --output vanity.html

Rails 3

There is currently an issue with report generation. The vanity-talk Google Group has a couple posts that outline the issue for now. This is one of the posts: http://groups.google.com/group/vanity-talk/browse_thread/thread/343081a72a0cefb6

If you are collecting data (in development you need to opt-in to this by setting Vanity.playground.collecting = true in environments/development.rb) you can view experiment results with the vanity dashboard instead of the report. 

The vanity dashboard setup instructions with Vanity work for Rails 3.x except the route is different. A Rails 3.x-style route would look like this:

  `match '/vanity(/:action(/:id(.:format)))', :controller=>:vanity`

Registering participants with Javascript

If robots or spiders make up a significant portion of your sites traffic they can affect your conversion rate. Vanity can optionally add participants to the experiments using asynchronous javascript callbacks, which will keep almost all robots out. To set this up simply do the following:

  • Add Vanity.playground.use_js!

  • Set Vanity.playground.add_participant_path = '/path/to/vanity/action', this should point to the add_participant path that is added with Vanity::Rails::Dashboard, make sure that this action is available to all users

  • Add <%= vanity_js %> to any page that needs uses an ab_test. vanity_js needs to be included after your call to ab_test so that it knows which version of the experiment the participant is a member of. The helper will render nothing if the there are no ab_tests running on the current page, so adding vanity_js to the bottom of your layouts is a good option. Keep in mind that if you call use_js! and don't include vanity_js in your view no participants will be recorded.


  • Fork the project

  • Please use a topic branch to make your changes, it's easier to test them that way

  • Fix, patch, enhance, document, improve, sprinkle pixie dust

  • At minimum run rake test, if possible, please run rake test:all

  • Tests. Please. Run rake test, of if you can, rake test:all

  • Send a pull request on GitHub


Original code, copyright of Assaf Arkin, released under the MIT license.

Documentation available under the Creative Commons Attribution license.

For full list of credits and licenses: vanity.labnotes.org/credits.html.