The project is in a healthy, maintained state
Oaken aims to blend your Fixtures/Factories and levels up your database seeds.
 Project Readme


Oaken is a new take on development and test data management for your Rails app. It blends the stability and storytelling from Fixtures with the dynamicness of FactoryBot/Fabricator.

Fixtures are stable & help you build a story of how your app and its object graph exists along with edge cases, but the UX is unfortunately a nightmare. To trace N associations, you have to open and read N different files — there's no way to group by scenario.

FactoryBot is spray & pray. You basically say “screw it, just give me the bare minimum I need to run this test”, which slows everything down because there’s no cohesion; and the Factories are always suspect in terms of completeness. Sure, I got the test to pass by wiring these 5 Factories together but did I miss something?

Oaken instead upgrades seeds in db/seeds.rb, so that you can put together scenarios & also reuse the development data in tests. That way the data you see in your development browser, is the same data you work with in tests to tie it more together — especially for people who are new to your codebase.

So you get the stability of named keys, a cohesive dataset, and a story like Fixtures. But the dynamics of FactoryBot as well. And unlike FactoryBot, you’re not making tons of one-off records to handle each case.

While Fixtures and FactoryBot both load data & truncate in tests, the end result is you end up writing less data back & forth to the database because you aren’t cobbling stuff together.


Starting in development

You can set it up in db/seeds.rb, like this:

Oaken.prepare do
  seed :accounts, :data

This will look for deeply nested files to load in db/seeds and db/seeds/#{Rails.env} within the accounts and data directories.

Here's what they could look like:

# db/seeds/accounts/kaspers_donuts.rb
donuts = accounts.create :kaspers_donuts, name: "Kasper's Donuts"

kasper   = users.create :kasper,   name: "Kasper",   accounts: [donuts]
coworker = users.create :coworker, name: "Coworker", accounts: [donuts]

menu = menus.create account: donuts
plain_donut     = menu_items.create menu: menu, name: "Plain",     price_cents: 10_00
sprinkled_donut = menu_items.create menu: menu, name: "Sprinkled", price_cents: 10_10

supporter = users.create name: "Super Supporter"
orders.insert_all [user_id:, item_id:] * 10

orders.insert_all \ { { user_id: users.create(name: "Customer #{_1}").id, item_id: } }
# db/seeds/data/plans.rb
plans.upsert :basic, title: "Basic", price_cents: 10_00

Seed files will generally use create and/or insert. Passing a symbol to name the record is useful when reusing the data in tests.

Now you can run bin/rails db:seed and bin/rails db:seed:replant.

Interlude: Directory Naming Conventions

Oaken has some chosen directory conventions to help strengthen your understanding of your object graph:

  • Have a directory for your top-level model, like Account, Team, Organization, that's why we have db/seeds/accounts above.
  • db/seeds/data for any data tables, like the plans a SaaS app has.
  • db/seeds/tests/cases for any specific cases that are only used in some tests, like pagination.rb.

Reusing data in tests

With the setup above, Oaken can reuse the same data in tests like this:

# test/test_helper.rb
class ActiveSupport::TestCase
  include Oaken::TestSetup

Now tests have access to accounts.kaspers_donuts and users.kasper etc. that were setup in the data scripts.

You can also load a specific seed, like this:

class PaginationTest < ActionDispatch::IntegrationTest
  setup { seed "cases/pagination" }


We're recommending having one-off seeds on an individual unit of work to help reinforce test isolation. Having some seed files be isolated also helps:

  • Reduce amount of junk data generated for unrelated tests
  • Make it easier to debug a particular test
  • Reduce test flakiness
  • Encourage writing seed files for specific edge-case scenarios

Fixtures Converter

You can convert your Rails fixtures to Oaken's seeds by running:

$ bin/rails generate oaken:convert:fixtures

This will convert anything in test/fixtures to db/seeds. E.g. test/fixtures/users.yml becomes db/seeds/users.rb.


Install the gem and add to the application's Gemfile by executing:

$ bundle add oaken

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install oaken


After checking out the repo, run bin/setup to install dependencies. Then, run cd test/dummy and bin/rails test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Oaken project's codebases, issue trackers, chat rooms, and mailing lists is expected to follow the code of conduct.


Initial development is supported in part by:

And by:

As a sponsor you're welcome to submit a pull request to add your own name here.