rigor-actionmailer

Validates Mailer.action(args).deliver_* call sites for action existence and argument arity, and flags mailer actions whose view template is missing under app/views/. Actions inherited from included concern modules are merged into the mailer’s action set, so a mailer that derives its actions from included Emails::* concerns still type-checks. No Rails runtime dependency.

It ships bundled in rigortype. Activate it under plugins::

plugins:
  - rigor-actionmailer

What it checks

demo.rb:7:1:  info:  `UserMailer.welcome` matches mailer action (arity 1..2)
errors_demo.rb:7:1:  error: `UserMailer.welcome` expects 1..2 argument(s), got 0
errors_demo.rb:15:1: error: `UserMailer.does_not_exist` is not a defined mailer action (known actions: digest, reset_password, welcome)
app/mailers/user_mailer.rb:14:7: warning: `UserMailer#digest` has no view template under `app/views/user_mailer/`

1. Action existence — Mailer.unknown_action(...) → unknown-action (an unresolved include silences this rather than guessing).
2. Argument arity — too few / too many positional args → wrong-arity.
3. View template existence — each action needs at least one app/views/<mailer_underscore>/<action>.{html,text}.{erb,haml,slim}; a missing one → missing-view, anchored on the action’s def.

Recognised call shapes: a direct action call (UserMailer.welcome(user)), a .with(...) chain (UserMailer.with(user: u).welcome(user)), and a trailing .deliver_now / .deliver_later (accepted, not interpreted).

Configuration

plugins:
  - gem: rigor-actionmailer
    config:
      mailer_search_paths: ["app/mailers"]                            # default
      mailer_base_classes: ["ApplicationMailer", "ActionMailer::Base"] # default
      views_root: "app/views"                                         # default

Limitations

• Direct-superclass match only. class CustomerMailer < BaseMailer where BaseMailer < ApplicationMailer is not discovered unless BaseMailer is in mailer_base_classes. (Actions from included concern modules are merged; this is about the superclass chain.)
• Syntactic action list. Actions are read from instance-side defs; define_method, initialize, and _-prefixed names are excluded.
• Standard view filename pattern only (<action>.{html,text}.{erb,haml,slim}); custom engines / view paths are out of scope.
• A brand-new view file does not invalidate the cached index until something the mailer file touches changes (the read-tracking trade-off).

Plugin internals

The mailer/concern discoverer, the cached :mailer_index producer, the demo, and the contract surfaces this plugin exercises are in the plugin’s README. To write a plugin, see examples/ and the rigor-plugin-author skill.