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Gem Version

The main goal of the project is to provide an easy way to maintain FactoryBot inside your project in a good shape.

If the project helps you or your organization, I would be very grateful if you contribute or donate.
Your support is an incredible motivation and the biggest reward for my hard work.

Follow me and stay tuned for the updates:

What it does?

Currently, it helps to find unused factories and traits.

Example output (from Rails RSpec Example):

$ FB_TRACE=1 rspec
total number of unique used factories & traits: 3
total number of unique unused factories & traits: 3
unused factory admin => spec/factories.rb:10
unused trait with_address of factory admin => spec/factories.rb:11
unused global trait with_email => spec/factories.rb:16


Add this line to your application's Gemfile in the group you have factory_bot or factory_bot_rails:

gem 'factory_trace'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install factory_trace


For now, the gem supports RSpec out of the box. You don't need to add any hooks. Just run the specs, e.g.

# output to STDOUT
FB_TRACE=1 rspec
# OR output to any file
FB_TRACE_FILE=log/factory_trace.txt rspec

For any other case, add the following line where you want to start tracking usage of FactoryBot factories and traits:


Add this line where you want to stop tracking and get collected information:


Partial execution

Imagine, you run your specs in parts (as many as you need) and then want to track total usage of factories and traits. For that, we have a trace_only mode. You can try following commands here.

# one part
FB_TRACE=trace_only FB_TRACE_FILE=fb_trace_result1.json bundle exec rspec spec/first_spec.rb
# another part
FB_TRACE=trace_only FB_TRACE_FILE=fb_trace_result2.json bundle exec rspec spec/second_spec.rb
# output the usage to the console
bundle exec factory_trace fb_trace_result1.json fb_trace_result2.json
# or to the file
FB_TRACE_FILE=fb_report.txt bundle exec factory_trace fb_trace_result1.json fb_trace_result2.json

Note: bundle exec factory_trace won't load your project. Thus it runs fast and it's easier to configure it on CI.


You can configure FactoryTrace:

FactoryTrace.configure do |config|
  # default ENV.key?('FB_TRACE') || ENV.key?('FB_TRACE_FILE')
  config.enabled = true

  # default is ENV['FB_TRACE_FILE']
  # when nil outputs to STDOUT
  config.path = 'log/factory_trace.txt'

  # default is true when +path+ is nil
  config.color = true

  # default is ENV['FB_TRACE'] || :full
  # can be :full or :trace_only
  config.mode = :full

  # used to trace definitions places
  # default is true
  # can be true or false  
  config.trace_definition = true

Tip: if you have some errors try to disable trace_definition. That functionality does many monkey patches to FactoryBot. I will appreciate sharing an error stack trace so I can fix it.


After checking out the repo, run bundle install to install dependencies. Then, run rake spec to run the tests. 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 tags, and push the .gem file to


Open Collective Backers

You're an individual who wants to support the project with a monthly donation. Your logo will be available on the Github page. [Become a backer]

Open Collective Sponsors

You're an organization that wants to support the project with a monthly donation. Your logo will be available on the Github page. [Become a sponsor]


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


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

Code of Conduct

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


FactoryTrace's changelog is available here.


Copyright (c) Evgeniy Demin. See LICENSE.txt for further details.