Trigger MiniTest failures in Rails when Bullet detects N+1 query violations

bullet_and_minitest.md

In test/test_helper.rb...

### Bullet (N+1 queries)

if ENV['BULLET']
  Bullet.enable = true

  require 'minitest/unit'

  module MiniTestWithBullet
    def before_setup
      Bullet.start_request
      super if defined?(super)
    end

    def after_teardown
      super if defined?(super)

      if Bullet.warnings.present?
        warnings = Bullet.warnings.map{ |_k, warning| warning }.flatten.map{|warn| warn.body_with_caller}.join("\n-----\n\n")

        flunk(warnings)
      end

      Bullet.end_request
    end
  end

  class ActiveSupport::TestCase
    include MiniTestWithBullet
  end
end

module BulletHelper
  def before_setup
    Bullet.start_request
    super if defined?(super)
  end

  def after_teardown
    super if defined?(super)

    Bullet.perform_out_of_channel_notifications if Bullet.notification?
    Bullet.end_request
  end
end

Tested with ActiveSupport::TestCase on Rails 6.x

Thanks for sharing.

I'm using Rails 4.2.11 & the configuration above raised bullet errors/detections, but wasn't showing a useful stack trace. I found using after_setup & before_teardown gave me the real stack trace in testing.

module BulletHelper
  def after_setup
    Bullet.enable = true
    # Bullet.bullet_logger = true
    Bullet.unused_eager_loading_enable = false
    Bullet.raise = true # raise an error if n+1 query occurs
    Bullet.start_request
    super
  end

  def before_teardown
    super
    Bullet.perform_out_of_channel_notifications if Bullet.notification?
    Bullet.end_request
    Bullet.enable = false
    # Bullet.bullet_logger = false
    Bullet.raise = false
  end
end

class ActiveSupport::TestCase
  include BulletHelper
...

Also, using after_setup/before_teardown instead of before_setup/after_teardown allows to update the Bullet config in setup and teardown like this :

    setup do
      Bullet.unused_eager_loading_enable = false
    end

    teardown do
      Bullet.unused_eager_loading_enable = true
    end

Using before_setup/after_teardown, this code can fail because Bullet will check for unused eager loading after we re-enabled the setting and Bullet will then emit an error.