Report Rails deprecation warnings to Honeybadger (useful in production if there might be lines of code not covered by your tests - the horror!). Place this in your config/environments/production.rb

gistfile1.rb

ActiveSupport::Notifications.subscribe('deprecation.rails') do |name, start, finish, id, payload|
  Honeybadger.notify(
    error_class:   "DEPRECATION WARNING",
    error_message: payload[:message],
    backtrace:     payload[:callstack]
  )
end