Vignette

Vignette makes it dead simple to run reliable A/b tests in your Rails project.

Examples

Vignette is as simple as sampling from an Array:

@price = [5, 10, 15].vignette

We've also added a filter to HAML for running quick A/b tests:

h1
  :vignette
    Welcome to the Zoo.
    Come to see the Lions!
    Don't get caught by a lemur!

Installation

Add this line to your application's Gemfile:

gem 'vignette'

And then execute:

$ bundle

Or install it yourself as:

$ gem install vignette

Usage

Vignette was crafted to make A/b testing as simple as possible. Simply run the vignette function on any Array and get the result from a A/b test. Vignette will store this choice in session, a cookies or nowhere, based on how you configure Vignette. If you're in the request cycle (within an around_filter), Vignette will grab session or cookies for you. Otherwise, you'll need to specify where to store the result (if you want it consistent for the end-user). Vignette tests are identified by a checksum of the Array, and thus, changing the Array results in a new test.

# To store in session (default)
Vignette.init(store: :session)

# To use cookies
Vignette.init(store: :cookies)

# Or random sampling [no persistence]
Vignette.init(store: :random)

# Other options
Vignette.init(logging: true) # add debug logging

Running a Vignette test in your application:

[ 1,2,3 ].vignette # Chooses an option and stores test as indicated above
%w{one two three}.vignette # Same with strings

# or in HAML

:vignette
  Test one
  Test <strong>two</strong>
  Test #{three}

The choices for these tests are exposed through the Vignette.test method:

Vignette.test -> { '(app/views/users/new.html.haml:35)' => 'Test one' } # First choice was select for new.html.haml test line 35

You may store these values as properties in your analytics system.

Caveats

Tests are stored in your store object based on the original input. If you change the input of the test (regardless of the name), a new test will be created. Thus [1,2,3].vignette(:numbers) and [2,3,4].vignette(:numbers) will always be considered unique tests. New tests will overwrite old tests with the same name in Vignette.tests. This is by design so that you can update the test, have new results, but keep the same test name in your analytics system.

Note, you must use arrays that will not change between runs. Thus, [Date.today, 1.days.ago].vignette will end up creating separate tests every time this code is run. We use a Zlib.crc32 check to check for uniqueness of an array. Instead, this should be [0,1].vignette.days.ago.

If you choose to store your tests in cookies, then the chosen result will be stored in a cookie sent to the user's browser. Thus, be careful not to store any secret information in a test.

Naming Tests

Vignette tests can also be specifically named, e.g:

@cat_name = ["Chairman Meow", "Katy Purry"].vignette(:cat_names)

or from HAML:

div
  :vignette
    [dog_names]
    Wooferson
    T-Bone

This will lead to Vignette.tests to include: { "cat_names" => "Chairman Meow" }

Without a name, Vignettes will try to name themselves based on the name of the falling calling them, e.g. (app/models/user.rb:25) or (app/views/users/new.html.haml:22)

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Ensure test cases are passing (bundle exec rspec)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request