Next Rails

This is a toolkit to upgrade your next Rails application. It will help you set up dual booting, track deprecation warnings, and get a report on outdated dependencies for any Rails application.

This project is a fork of ten_years_rails


This gem started as a companion to the "Ten Years of Rails Upgrades" conference talk by Jordan Raine.

You'll find various utilities that we use at Clio to help us prepare for and complete Rails upgrades.

These scripts are still early days and may not work in every environment or app.

I wouldn't recommend adding this to your Gemfile long-term. Rather, try out the scripts and use them as a point of reference. Feel free to tweak them to better fit your environment.



Learn about your Gemfile and see what needs updating.

# Show all out-of-date gems
bundle_report outdated
# Show five oldest, out-of-date gems
bundle_report outdated | head -n 5
# Show gems that don't work with Rails 5.2.0
bundle_report compatibility --rails-version=5.2.0
bundle_report --help

Deprecation tracking

If you're using RSpec, add this snippet to rails_helper.rb or spec_helper.rb (whichever loads Rails).

RSpec.configure do |config|
  # Tracker deprecation messages in each file
      shitlist_path: "spec/support/deprecation_warning.shitlist.json",
      transform_message: -> (message) { message.gsub("#{Rails.root}/", "") }

We don't use MiniTest, so there isn't a prebuilt config for it but I suspect it's pretty similar to DeprecationTracker.track_rspec.

Once you have that, you can start using deprecation tracking in your tests:

# Run your tests and save the deprecations to the shitlist
# Run your tests and raise an error when the deprecations change

deprecations command

Once you have stored your deprecations, you can use deprecations to display common warnings, run specs, or update the shitlist file.

deprecations info
deprecations info --pattern "ActiveRecord::Base"
deprecations run
deprecations --help # For more options and examples

Right now, the path to the shitlist is hardcoded so make sure you store yours at spec/support/deprecations.shitlist.json.

Dual-boot Rails next

This command helps you dual-boot your application.

next --init         # Create and
vim Gemfile         # Tweak your dependencies conditionally using `next?`
next bundle install # Install new gems
next rails s        # Start server using


Add this line to your application's Gemfile:

gem 'next_rails'

And then execute:

$ bundle

Or install it yourself as:

$ gem install next_rails



$ next --init

Init will create a and an initialized The is initialized with the contents of your existing Gemfile.lock lock file. We initialize the to prevent major version jumps when running the next version of Rails.


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