How to verify controller actions are defined for all routes in a rails application?

Question

Is there a way to verify that all controller actions, as defined in config/routes.rb and exposed by rake routes, actually correspond to an existing controller action?

For example, suppose we have the following routes file:

Application.routes.draw do
  resources :foobar
end

And the following controller:

class FoobarsController < ApplicationController
  def index
    # ...
  end

  def show
    # ...
  end
end

I'd like to have some way of auto-detecting that the create, new, edit, update and destroy actions (as implicitly defined by the routes) are not mapped to a valid controller action - so that I can fix the routes.rb file:

Application.routes.draw do
  resources :foobar, only: [:index, :show]
end

An "integrity check" of the routes, if you will.

Such a check wouldn't necessarily need to be perfect; I could easily verify any false positives manually. (Although a "perfect" check would be ideal, as it could be included in the test suite!)

My motivation here is to prevent AbstractController::ActionNotFound exceptions from being raised by dodgy API requests, as additional routes were inadvertently defined (in a large application).

Answer 1

I got curious, and the following is my attempt. It's still not accurate because it does not yet match proper format. Also, some routes have constraints; my code doesn't yet consider.

rails console:

todo_skipped_routes = []
valid_routes = []
invalid_routes = []

Rails.application.routes.routes.each do |route|
  controller_route_name = route.defaults[:controller]
  action_route_name = route.defaults[:action]

  if controller_route_name.blank? || action_route_name.blank?
    todo_skipped_routes << route
    next
  end

  # TODO: maybe Rails already has a "proper" way / method to constantize this
  # copied over @max answer, because I forgot to consider namespacing
  controller_class = "#{controller_route_name.sub('\/', '::')}_controller".camelcase.safe_constantize

  is_route_valid = !controller_class.nil? && controller_class.instance_methods(false).include?(action_route_name.to_sym)

  # TODO: check also if "format" matches / gonna be "responded to" properly by the controller-action
  #   check also "lambda" constraints, and `request.SOMEMETHOD` constraints (i.e. `subdomain`, `remote_ip`,  `host`, ...)

  if is_route_valid
    valid_routes << route
  else
    invalid_routes << route
  end
end

puts valid_routes
puts invalid_routes

# puts "friendlier" version
pp invalid_routes.map(&:defaults)
# => [
#  {:controller=>"sessions", :action=>"somenonexistingaction"},
#  {:controller=>"posts", :action=>"criate"},
#  {:controller=>"yoosers", :action=>"create"},
# ]

I am also interested to know other answers, or if there is a proper way to do this. Also, if anyone knows an improvement over my code, please let me know. Thanks :)