# Split

Split is a rack based ab testing framework designed to work with Rails, Sinatra or any other rack based app.

Split is heavily inspired by the Abingo and Vanity rails ab testing plugins and Resque in its use of Redis.

Split is designed to be hacker friendly, allowing for maximum customisation and extensibility.

## Requirements

Split uses redis as a datastore.

Split only supports redis 2.0 or greater.

If you're on OS X, Homebrew is the simplest way to install Redis:

    $ brew install redis
    $ redis-server /usr/local/etc/redis.conf

You now have a Redis daemon running on 6379.

## Setup

If you are using bundler add split to your Gemfile:

    gem 'split'

Then run:

    bundle install

Otherwise install the gem:

    gem install split

and require it in your project:

    require 'split'

### SystemTimer

If you are using Redis on Ruby 1.8.x then you will likely want to also use the SystemTimer gem if you want to make sure the Redis client will not hang.

Put the following in your gemfile as well:

    gem 'SystemTimer'

### Rails

Split is autoloaded when rails starts up, as long as you've configured redis it will 'just work'.

### Sinatra

To configure sinatra with Split you need to enable sessions and mix in the helper methods. Add the following lines at the top of your sinatra app:

    class MySinatraApp < Sinatra::Base
      enable :sessions
      helpers Split::Helper

      get '/' do
      ...
    end

## Usage

To begin your ab test use the `ab_test` method, naming your experiment with the first argument and then the different variants which you wish to test on as the other arguments.

`ab_test` returns one of the alternatives, if a user has already seen that test they will get the same alternative as before, which you can use to split your code on.

It can be used to render different templates, show different text or any other case based logic.

`finished` is used to make a completion of an experiment, or conversion.

Example: View

    <% ab_test("login_button", "/images/button1.jpg", "/images/button2.jpg") do |button_file| %>
      <%= img_tag(button_file, :alt => "Login!") %>
    <% end %>

Example: Controller

    def register_new_user
      # See what level of free points maximizes users' decision to buy replacement points.
      @starter_points = ab_test("new_user_free_points", 100, 200, 300)
    end

Example: Conversion tracking (in a controller!)

    def buy_new_points
      # some business logic
      finished("buy_new_points")
    end

Example: Conversion tracking (in a view)

    Thanks for signing up, dude! <% finished("signup_page_redesign") >

You can find more examples, tutorials and guides on the [wiki](https://github.com/andrew/split/wiki).

## Extras

### Weighted alternatives

Perhaps you only want to show an alternative to 10% of your visitors because it is very experimental or not yet fully load tested.

To do this you can pass a weight with each alternative in the following ways:

    ab_test('homepage design', 'Old' => 20, 'New' => 2)

    ab_test('homepage design', 'Old', {'New' => 0.1})

    ab_test('homepage design', {'Old' => 10}, 'New')

This will only show the new alternative to visitors 1 in 10 times, the default weight for an alternative is 1.

### Overriding alternatives

For development and testing, you may wish to force your app to always return an alternative.
You can do this by passing it as a parameter in the url.

If you have an experiment called `button_color` with alternatives called `red` and `blue` used on your homepage, a url such as:

    http://myawesomesite.com?button_color=red

will always have red buttons. This won't be stored in your session or count towards to results.

### Reset after completion

When a user completes a test their session is reset so that they may start the test again in the future.

To stop this behaviour you can pass the following option to the `finished` method:

    finished('experiment_name', :reset => false)

The user will then always see the alternative they started with.

## Web Interface

Split comes with a Sinatra-based front end to get an overview of how your experiments are doing.

If you are running Rails 2: You can mount this inside your app using Rack::URLMap in your `config.ru`

    require 'split/dashboard'

    run Rack::URLMap.new \
      "/"       => Your::App.new,
      "/split" => Split::Dashboard.new

However, if you are using Rails 3: You can mount this inside your app routes by first adding this to the Gemfile:

    gem 'split', :require => 'split/dashboard'

Then adding this to config/routes.rb

    mount Split::Dashboard, :at => 'split'

You may want to password protect that page, you can do so with `Rack::Auth::Basic`

    Split::Dashboard.use Rack::Auth::Basic do |username, password|
      username == 'admin' && password == 'p4s5w0rd'
    end

## Configuration

You can override the default configuration options of Split like so:

    Split.configure do |config|
      config.robot_regex = /my_custom_robot_regex/
      config.ignore_ip_addresses << '81.19.48.130'
    end

### Redis

You may want to change the Redis host and port Split connects to, or
set various other options at startup.

Split has a `redis` setter which can be given a string or a Redis
object. This means if you're already using Redis in your app, Split
can re-use the existing connection.

String: `Split.redis = 'localhost:6379'`

Redis: `Split.redis = $redis`

For our rails app we have a `config/initializers/split.rb` file where
we load `config/split.yml` by hand and set the Redis information
appropriately.

Here's our `config/split.yml`:

    development: localhost:6379
    test: localhost:6379
    staging: redis1.example.com:6379
    fi: localhost:6379
    production: redis1.example.com:6379

And our initializer:

    rails_root = ENV['RAILS_ROOT'] || File.dirname(__FILE__) + '/../..'
    rails_env = ENV['RAILS_ENV'] || 'development'

    split_config = YAML.load_file(rails_root + '/config/split.yml')
    Split.redis = split_config[rails_env]

## Namespaces

If you're running multiple, separate instances of Split you may want
to namespace the keyspaces so they do not overlap. This is not unlike
the approach taken by many memcached clients.

This feature is provided by the [redis-namespace][rs] library, which
Split uses by default to separate the keys it manages from other keys
in your Redis server.

Simply use the `Split.redis.namespace` accessor:

    Split.redis.namespace = "split:blog"

We recommend sticking this in your initializer somewhere after Redis
is configured.

## Extensions

  - [Split::Export](http://github.com/andrew/split-export) - easily export ab test data out of Split
  - [Split::Analytics](http://github.com/andrew/split-analytics) - push test data to google analytics

## Contributors

Special thanks to the following people for submitting patches:

* Lloyd Pick
* Jeffery Chupp
* Andrew Appleton

## Development

Source hosted at [GitHub](http://github.com/andrew/split).
Report Issues/Feature requests on [GitHub Issues](http://github.com/andrew/split/issues).

Tests can be ran with `rake spec`

### Note on Patches/Pull Requests

 * Fork the project.
 * Make your feature addition or bug fix.
 * Add tests for it. This is important so I don't break it in a
   future version unintentionally.
 * Commit, do not mess with rakefile, version, or history.
   (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
 * Send me a pull request. Bonus points for topic branches.

## Copyright

Copyright (c) 2011 Andrew Nesbitt. See [LICENSE](https://github.com/andrew/split/blob/master/LICENSE) for details.