Experiment Driven Development for Ruby
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Latest commit c2bf28b Jan 13, 2017 @phillbaker phillbaker committed with phillbaker Fix missing `Vanity` module in `track!` call.
Fixes #320.




Vanity is an A/B testing framework for Rails that is datastore agnostic.


A/B Testing With Rails

Step 1: Start using Vanity in your Rails application

Step 1.1

Rails 3 & Rails 4 installation

Add to your Gemfile:

gem "vanity"

(For support for older versions of Rails and Ruby 1.8, please see the 1.9.x branch.)

Step 1.2

Choose a datastore that best fits your needs and preferences for storing experiment results. Choose one of: Redis, MongoDB or an SQL database. While Redis is usually faster, it may add additional complexity to your stack. Datastores should be configured using a config/vanity.yml.

Redis Setup

Add to your Gemfile:

gem "redis", ">= 2.1"
gem "redis-namespace", ">= 1.1.0"

By default Vanity is configured to use Redis on localhost port 6379 with database 0.

A sample config/vanity.yml might look like:

  collecting: false
  adapter: redis
  url: redis://<%= ENV["REDIS_USER"] %>:<%= ENV["REDIS_PASSWORD"] %>@<%= ENV["REDIS_HOST"] %>:<%= ENV["REDIS_PORT"] %>/0

If you want to use your test environment with RSpec you will need to add an adapter to test:

  adapter: redis
  collecting: false

To re-use an existing redis connection, you can call Vanity.connect! explicitly, for example:

  adapter: :redis,
  redis: $redis
MongoDB Setup

Add to your Gemfile:

gem "mongo", "~> 2.0" # For Mongo 1.x support see Vanity versions 2.1 and below.

A sample config/vanity.yml might look like:

  adapter: mongodb
  database: analytics
  collecting: false
  adapter: mongodb
  database: analytics
SQL Database Setup

Vanity supports multiple SQL stores (like MySQL, MariaDB, Postgres, Sqlite, etc.) using ActiveRecord, which is built into Rails. If you're using DataMapper, Sequel or another persistence framework, add to your Gemfile:

    gem "active_record"

A sample config/vanity.yml might look like:

  adapter: active_record
  active_record_adapter: sqlite3
  database: db/development.sqlite3
  adapter: active_record
  active_record_adapter: default
  collecting: false
  active_record_adapter: postgresql
  <% uri = URI.parse(ENV['DATABASE_URL']) %>
  host:     <%= uri.host %>
  username: <%= uri.username %>
  password: <%= uri.password %>
  port:     <%= uri.port %>
  database: <%= uri.path.sub('/', '') %>

If you're going to store data in the database, run the generator and migrations to create the database schema:

$ rails generate vanity
$ rake db:migrate
Forking servers and reconnecting

If you're using a forking server (like Passenger or Unicorn), you should reconnect after a new worker is created:

# unicorn.rb
after_fork do |server, worker|
  defined?(Vanity) && Vanity.reconnect!

# an initializer
if defined?(PhusionPassenger)
  PhusionPassenger.on_event(:starting_worker_process) do |forked|
    # We're in smart spawning mode.
    if forked
      defined?(Vanity) && Vanity.reconnect!

If you're using explicit options with Vanity.connect!, you should call disconnect! first, for example:

  adapter: 'redis',
  redis: $redis

Step 1.3

Turn Vanity on, and pass a reference to a method that identifies a user. For example:

class ApplicationController < ActionController::Base
  use_vanity :current_user

For more information, please see the identity documentation.

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

If the experiment uses a metric as above ("signups"), there needs to be a corresponding ruby file for that metric, experiments/metrics/signups.rb.

metric "Signup (Activation)" do
  description "Measures how many people signed up for our awesome service."

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

Conversions are created via the Vanity.track! method. For example:

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

Step 5: Check the report:

vanity report --output vanity.html

To view metrics and experiment results with the dashboard in Rails 3 & Rails 4:

rails generate controller Vanity --helper=false

In config/routes.rb, add:

get '/vanity' =>'vanity#index'
get '/vanity/participant/:id' => 'vanity#participant'
post '/vanity/complete'
post '/vanity/chooses'
post '/vanity/reset'
post '/vanity/enable'
post '/vanity/disable'
post '/vanity/add_participant'
get '/vanity/image'

The controller should look like:

class VanityController < ApplicationController
  include Vanity::Rails::Dashboard
  layout false  # exclude this if you want to use your application layout

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 many robots out. For those robots that do execute Javascript and are well-behaved (like Googlebot), Vanity filters out requests based on their user-agent string.

In Rails, add the following to application.rb:

Vanity.configure do |config|
  config.use_js = true

  # Optionally configure the add_participant route that is added with Vanity::Rails::Dashboard,
  # make sure that this action does not require authentication
  # config.add_participant_route = '/vanity/add_participant'

Then add <%= vanity_js %> to any page that calls an A/B test after calling 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 set use_js and don't include vanity_js in your view no participants will be recorded.


Here's what's tested and known to work:

Ruby 2.1
  Persistence: Redis, Mongo, ActiveRecord
  Rails: 3.2, 4.1, 4.2
Ruby 2.2
  Persistence: Redis, Mongo, ActiveRecord
  Rails: 3.2, 4.1, 4.2, 5
Ruby 2.3
  Persistence: Redis, Mongo, ActiveRecord
  Rails: 3.2, 4.1, 4.2, 5
JRuby 1.9
  Persistence: Redis, Mongo, ActiveRecord
  Rails: 3.2, 4.1, 4.2


For view tests/specs or integration testing, it's handy to set the outcome of an experiment. This may be done using the chooses method. For example:


See the docs on testing for more.

Updating documentation

Documenation is written in the textile format in the docs directory, and is hosted on Github Pages. To update the docs commit changes to the master branch in this repository, then:

bundle exec rake docs # output HTML files into html/
git checkout gh-pages
mv html/* . # Move generated html to the top of the repo
git commit # Add, commit and push any changes!

Go ahead and target a pull request against the gh-pages branch.


  • Fork the project
  • Please use a feature branch to make your changes, it's easier to test them that way
  • To set up the test suite run bundle, then run appraisal install to prepare the test suite to run against multiple versions of Rails
  • Fix, patch, enhance, document, improve, sprinkle pixie dust
  • Tests. Please. Run appraisal rake test, of if you can, rake test:all. (This project uses Travis CI where the test suite is run against multiple versions of ruby, rails and backends.)
  • 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: http://vanity.labnotes.org/credits.html.