Fixation

This gem will precompile the SQL statements needed to clear and repopulate your test tables with fixtures when the app boots under spring, so that spec startup just needs to run a small number of multi-row SQL statements to prepare for run. This takes around 1/10th the time as a normal fixture load.

Like ActiveRecord's normal fixture implementation, Fixation will load the model classes in order to use metadata about associations and enums. But since Fixation is run at the time spring starts, Fixation will then 'reload' rails (the same way spring does), so you can change your model classes and re-run tests without having to restart spring.

Add this gem to your application's Gemfile:

groups :development, :test do
  gem 'fixation'
end

And then execute:

$ bundle

Or install it yourself as:

$ gem install fixation

Then, make an initializer file in config/initializers:

if Rails.env.test? && Fixation.running_under_spring?
  Rails.application.config.after_initialize do
    Fixation.preload_for_spring
  end
end

Open up your spec_helper.rb, and find the current global_fixtures setting:

config.global_fixtures = :all

Change that to [] so that ActiveRecord doesn't load the fixtures again itself, and load the Fixation module:

config.global_fixtures = []
config.include Fixation.fixture_methods

Finally run spring stop so these changes get picked up.

Simply run your tests under spring.

bundle exec spring spec/models/my_spec.rb

You'll need to run rake tasks like db:create and db:test:prepare the normal way (without spring), because if the database doesn't exist or the schema isn't loaded, the initializer above will asplode.

Not all features of regular ActiveRecord fixtures are supported:

• HABTM support has not been implemented (does anyone use HABTM these days?)

Unlike regular ActiveRecord fixtures, Fixation supports looking for fixture files in multiple paths. It defaults to looking in test/fixtures and spec/fixtures. You can change this in your initializer before you do the spring setup:

if Rails.env.test?
  Fixation.paths = %w(spec/fixtures db/seeds)
end

if Rails.env.test? && Fixation.running_under_spring?
  Rails.application.config.after_initialize do
    Fixation.preload_for_spring
  end
end

Fixation will load files with either the .yml or .yml.erb extension from the configured fixture paths. You can change this in your initializer in a similar fashion to the fixture paths:

if Rails.env.test?
  Fixation.extensions = %w(.yml .other.extension)
end

By default Fixation will only reset those tables that have a fixture file, like Rails. Optionally, you can tell it to clear all other tables so that you don't need to make empty fixture files.

if Rails.env.test?
  Fixation.clear_other_tables = true
end

As well as traditional .yml fixture files, Fixation allows you to drop .rb files into your fixture directory. You can then call the add_fixture method, passing the name of the table, the name of the fixture, and the attributes:

10.times do |n|
  Fixation.add_fixture(:customers, "active_customer_#{n}", active: true, name: "Sue #{n}")
end

(You should avoid accessing your actual model classes here, since that will cause them to be auto-loaded.)

When debugging difficult test scenarios, it can be useful to confirm which record you are looking at. As well as the usual forward mappings from fixture name to record, Fixation supports mapping back from record or record ID to the fixture name.

For example, if customers(:jeff) returns a record with ID 12345678, then customer_fixture_name_for_id(12345678) will return :jeff, as will customer_fixture_name_for_id(Customer.find(12345678)).

Bug reports and pull requests are welcome on GitHub at https://github.com/willbryant/fixation.

• Andy Newport (@newportandy)
• Andrew Clemons (@aclemons)

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