Support process.action_mailbox (#152)

README.md

@@ -172,7 +172,7 @@ These are Rails Instrumentation API hooks supported by this gem so far.
 
 | Event name                                                                                                                | Supported |
 | ------------------------------------------------------------------------------------------------------------------------- | --------- |
-| [`process.action_mailbox`](https://edgeguides.rubyonrails.org/active_support_instrumentation.html#process-action-mailbox) |           |
+| [`process.action_mailbox`](https://edgeguides.rubyonrails.org/active_support_instrumentation.html#process-action-mailbox) | ✅        |
 
 ### Railties
 

lib/rails_band.rb

@@ -53,4 +53,9 @@ module ActionCable
   module ActiveStorage
     autoload :LogSubscriber, 'rails_band/active_storage/log_subscriber'
   end
+
+  # RailsBand::ActionMailbox is responsible for subscribing notifications from ActionMailbox.
+  module ActionMailbox
+    autoload :LogSubscriber, 'rails_band/action_mailbox/log_subscriber'
+  end
 end

lib/rails_band/action_mailbox/event/process.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module RailsBand
+  module ActionMailbox
+    module Event
+      # A wrapper for the event that is passed to `process.action_mailbox`.
+      class Process < BaseEvent
+        def mailbox
+          @mailbox ||= @event.payload.fetch(:mailbox)
+        end
+
+        def inbound_email
+          @inbound_email ||= @event.payload.fetch(:inbound_email)
+        end
+      end
+    end
+  end
+end

lib/rails_band/action_mailbox/log_subscriber.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require 'rails_band/action_mailbox/event/process'
+
+module RailsBand
+  module ActionMailbox
+    # The custom LogSubscriber for ActionMailbox.
+    class LogSubscriber < ::ActiveSupport::LogSubscriber
+      mattr_accessor :consumers
+
+      def process(event)
+        consumer_of(__method__)&.call(Event::Process.new(event))
+      end
+
+      private
+
+      def consumer_of(sub_event)
+        consumers[:"#{sub_event}.action_mailbox"] || consumers[:action_mailbox] || consumers[:default]
+      end
+    end
+  end
+end

lib/rails_band/railtie.rb

@@ -66,6 +66,11 @@ class Railtie < ::Rails::Railtie
           swap.call(::ActiveJob::LogSubscriber, RailsBand::ActiveJob::LogSubscriber, :active_job)
         end
       end
+
+      if defined?(::ActionMailbox)
+        RailsBand::ActionMailbox::LogSubscriber.consumers = consumers
+        RailsBand::ActionMailbox::LogSubscriber.attach_to :action_mailbox
+      end
     end
   end
 end

test/dummy/app/controllers/users_controller.rb

@@ -133,6 +133,15 @@ def message_serializer_fallback
     redirect_to users_path
   end
 
+  def mailbox
+    ActiveSupport::Notifications.instrument('process.action_mailbox',
+                                            { mailbox: Object.new,
+                                              inbound_email: { id: 3, message_id: 'mid', status: 'processing' } }) do
+      # noop
+    end
+    redirect_to users_path
+  end
+
   private
 
   def halt!

test/dummy/config/routes.rb

@@ -15,6 +15,7 @@
     get :cache4
     get :deprecation
     get :message_serializer_fallback
+    get :mailbox
   end
 
   resources :yay, only: %i[index show]

test/rails_band/action_mailbox/event/action_mailbox_process_test.rb

@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ActionMailboxProcessTest < ActionDispatch::IntegrationTest
+  setup do
+    @event = nil
+    RailsBand::ActionMailbox::LogSubscriber.consumers = {
+      'process.action_mailbox': ->(event) { @event = event }
+    }
+    @user = User.create!(name: 'foo', email: '[email protected]')
+  end
+
+  test 'returns name' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_equal 'process.action_mailbox', @event.name
+  end
+
+  test 'returns time' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Float, @event.time
+  end
+
+  test 'returns end' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Float, @event.end
+  end
+
+  test 'returns transaction_id' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of String, @event.transaction_id
+  end
+
+  test 'returns cpu_time' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Float, @event.cpu_time
+  end
+
+  test 'returns idle_time' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Float, @event.idle_time
+  end
+
+  test 'returns allocations' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Integer, @event.allocations
+  end
+
+  test 'returns duration' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of Float, @event.duration
+  end
+
+  test 'calls #to_h' do
+    get "/users/#{@user.id}/mailbox"
+
+    %i[name time end transaction_id cpu_time idle_time allocations duration mailbox inbound_email].each do |key|
+      assert_includes @event.to_h, key
+    end
+  end
+
+  test 'calls #slice' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_equal({ name: 'process.action_mailbox' }, @event.slice(:name))
+  end
+
+  test 'returns an instance of Process' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_instance_of RailsBand::ActionMailbox::Event::Process, @event
+  end
+
+  test 'returns mailbox' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert @event.mailbox
+  end
+
+  test 'returns inbound_email' do
+    get "/users/#{@user.id}/mailbox"
+
+    assert_equal({ id: 3, message_id: 'mid', status: 'processing' }, @event.inbound_email)
+  end
+end

test/rails_band/action_mailbox/log_subscriber_test.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ActionMailboxLogSubscriberTest < ActionDispatch::IntegrationTest
+  setup do
+    @mock = Minitest::Mock.new
+    @mock.expect(:recv, nil)
+    @user = User.create!(name: 'bo', email: '[email protected]')
+  end
+
+  test 'use the consumer with the exact event name' do
+    RailsBand::ActionMailbox::LogSubscriber.consumers = {
+      'process.action_mailbox': ->(_event) { @mock.recv }
+    }
+    get "/users/#{@user.id}/mailbox"
+
+    assert_mock @mock
+  end
+
+  test 'use the consumer with namespace' do
+    RailsBand::ActionMailbox::LogSubscriber.consumers = {
+      action_mailbox: ->(event) { @mock.recv if event.name == 'process.action_mailbox' }
+    }
+    get "/users/#{@user.id}/mailbox"
+
+    assert_mock @mock
+  end
+
+  test 'use the consumer with default' do
+    RailsBand::ActionMailbox::LogSubscriber.consumers = {
+      default: ->(event) { @mock.recv if event.name == 'process.action_mailbox' }
+    }
+    get "/users/#{@user.id}/mailbox"
+
+    assert_mock @mock
+  end
+
+  test 'do not use the consumer because the event is not for the target' do
+    RailsBand::ActionMailbox::LogSubscriber.consumers = {
+      'unknown.action_mailbox': ->(_event) { @mock.recv }
+    }
+    get "/users/#{@user.id}/mailbox"
+    assert_raises MockExpectationError do
+      @mock.verify
+    end
+  end
+end