Find unused Rails routes

find_unused_routes.rb

require_relative "config/environment"
# Note: As of Rails 7.1+ we can just use:
# `rails routes --unused`

Rails.application.routes.routes.map(&:requirements).each do |route|
  next if route.blank?
  next if route[:internal]

  controller_name = "#{route[:controller].camelcase}Controller"
  next if controller_name.constantize.new.respond_to?(route[:action])

  implicit_render_view = Rails.root.join("app", "views", *route[:controller].split('::'), "#{route[:action]}.*")
  next if Dir.glob(implicit_render_view).any?

  puts "#{controller_name}##{route[:action]}"
rescue NameError, LoadError
  puts "#{controller_name}##{route[:action]} - controller not found"
end