Support class reloading for Event Subscribers

core/app/subscribers/spree/mailer_subscriber.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Spree
+  module MailerSubscriber
+    include Spree::Event::Subscriber
+
+    event_action :order_finalized
+    event_action :send_reimbursement_email, event_name: :reimbursement_reimbursed
+
+    def order_finalized(event)
+      order = event.payload[:order]
+      unless order.confirmation_delivered?
+        Spree::Config.order_mailer_class.confirm_email(order).deliver_later
+        order.update_column(:confirmation_delivered, true)
+      end
+    end
+
+    def send_reimbursement_email(event)
+      reimbursement = event.payload[:reimbursement]
+      Spree::Config.reimbursement_mailer_class.reimbursement_email(reimbursement.id).deliver_later
+    end
+  end
+end

core/lib/spree/core/engine.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require 'spree/config'
-require 'spree/event/processors/mailer_processor'
 
 module Spree
   module Core
@@ -45,8 +44,15 @@ class Engine < ::Rails::Engine
         Migrations.new(config, engine_name).check
       end
 
-      initializer 'spree.core.subscribe_event_mailer_processor' do
-        Spree::Event::Processors::MailerProcessor.subscribe!
+      # Setup Event Subscribers
+      initializer 'spree.core.initialize_subscribers' do |app|
+        app.reloader.to_prepare do
+          Spree::Event.subscribers.each(&:subscribe!)
+        end
+
+        app.reloader.before_class_unload do
+          Spree::Event.subscribers.each(&:unsubscribe!)
+        end
       end
 
       # Load in mailer previews for apps to use in development.

core/lib/spree/event.rb

@@ -21,7 +21,7 @@ module Event
     #     @order.finalize!
     #   end
     def fire(event_name, opts = {})
-      adapter.fire name_with_suffix(event_name), opts do
+      adapter.fire name_with_suffix(event_name.to_s), opts do
         yield opts if block_given?
       end
     end
@@ -98,6 +98,12 @@ def suffix
       Spree::Config.events.suffix
     end
 
+    # @!attribute [r] subscribers
+    #   @return [Array<Spree::Event::Subscriber>] A list of subscribers used to support class reloading for Spree::Event::Subscriber instances
+    def subscribers
+      Spree::Config.events.subscribers
+    end
+
     private
 
     def name_with_suffix(name)

core/lib/spree/event/configuration.rb

@@ -1,8 +1,16 @@
 # frozen_string_literal: true
 
+require 'spree/core/class_constantizer'
+
 module Spree
   module Event
     class Configuration
+      def subscribers
+        @subscribers ||= ::Spree::Core::ClassConstantizer::Set.new.tap do |set|
+          set << 'Spree::MailerSubscriber'
+        end
+      end
+
       attr_writer :adapter, :suffix
 
       def adapter

core/spec/lib/spree/event/subscriber_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 require 'spree/event'
 
-RSpec.describe Spree::Event do
+RSpec.describe Spree::Event::Subscriber do
   module M
     include Spree::Event::Subscriber
 

core/spec/lib/spree/event_spec.rb

@@ -14,21 +14,21 @@
     expect(subject.adapter).to eql Spree::Event::Adapters::ActiveSupportNotifications
   end
 
-  before do
-    # ActiveSupport::Notifications does not provide an interface to clean all
-    # subscribers at once, so some low level brittle code is required
-    @old_subscribers = notifier.instance_variable_get('@subscribers').dup
-    @old_listeners = notifier.instance_variable_get('@listeners_for').dup
-    notifier.instance_variable_get('@subscribers').clear
-    notifier.instance_variable_get('@listeners_for').clear
-  end
+  context 'with the default adapter' do
+    before do
+      # ActiveSupport::Notifications does not provide an interface to clean all
+      # subscribers at once, so some low level brittle code is required
+      @old_subscribers = notifier.instance_variable_get('@subscribers').dup
+      @old_listeners = notifier.instance_variable_get('@listeners_for').dup
+      notifier.instance_variable_get('@subscribers').clear
+      notifier.instance_variable_get('@listeners_for').clear
+    end
 
-  after do
-    notifier.instance_variable_set '@subscribers', @old_subscribers
-    notifier.instance_variable_set '@listeners_for', @old_listeners
-  end
+    after do
+      notifier.instance_variable_set '@subscribers', @old_subscribers
+      notifier.instance_variable_set '@listeners_for', @old_listeners
+    end
 
-  context 'with the default adapter' do
     describe '#listeners' do
       context 'when there is no subscription' do
         it { expect(subject.listeners).to be_empty }
@@ -89,4 +89,30 @@
       end
     end
   end
+
+  describe '.subscribers' do
+    let(:subscriber) { instance_double(Module, 'Subscriber') }
+    let(:subscriber_name) { instance_double(String, 'Subscriber name') }
+
+    before do
+      described_class.subscribers.clear
+      allow(subscriber).to receive(:name).and_return(subscriber_name)
+      allow(subscriber_name).to receive(:constantize).and_return(subscriber)
+      allow(subscriber_name).to receive(:to_s).and_return(subscriber_name)
+    end
+
+    it 'accepts the names of constants' do
+      Spree::Config.events.subscribers << subscriber_name
+
+      expect(described_class.subscribers.to_a).to eq([subscriber])
+    end
+
+    it 'discards duplicates' do
+      described_class.subscribers << subscriber_name
+      described_class.subscribers << subscriber_name
+      described_class.subscribers << subscriber_name
+
+      expect(described_class.subscribers.to_a).to eq([subscriber])
+    end
+  end
 end

core/spec/models/spree/order_spec.rb

@@ -29,14 +29,14 @@
       end
 
       # These specs show how notifications can be removed, one at a time or
-      # all the ones set by MailerProcessor module
+      # all the ones set by MailerSubscriber module
       context 'when removing the default email notification subscription' do
         before do
-          Spree::Event.unsubscribe Spree::Event::Processors::MailerProcessor.order_finalized_handler
+          Spree::Event.unsubscribe Spree::MailerSubscriber.order_finalized_handler
         end
 
         after do
-          Spree::Event::Processors::MailerProcessor.subscribe!
+          Spree::MailerSubscriber.subscribe!
         end
 
         it 'does not send the email' do
@@ -47,11 +47,11 @@
 
       context 'when removing all the email notification subscriptions' do
         before do
-          Spree::Event::Processors::MailerProcessor.unsubscribe!
+          Spree::MailerSubscriber.unsubscribe!
         end
 
         after do
-          Spree::Event::Processors::MailerProcessor.subscribe!
+          Spree::MailerSubscriber.subscribe!
         end
 
         it 'does not send the email' do

guides/source/developers/events/overview.html.md

@@ -25,7 +25,7 @@ Spree::Config.events.adapter = "Spree::EventBus.new"
 
 ## Subscribing to events
 
-`Spree::Event.subscribe` allows to subscribe to a certain event. The event name is mandatory, the optional block will be executed everytime the event is fired:
+`Spree::Event.subscribe` allows to subscribe to a certain event. The event name is mandatory, the optional block will be executed every time the event is fired:
 
 ```ruby
 Spree::Event.subscribe 'order_finalized' do |event|