Allow configuration of ActionMailer queue name

actionmailer/lib/action_mailer/base.rb

@@ -409,6 +409,8 @@ module ActionMailer
   #
   # * <tt>deliveries</tt> - Keeps an array of all the emails sent out through the Action Mailer with
   #   <tt>delivery_method :test</tt>. Most useful for unit and functional testing.
+  #
+  # * <tt>deliver_later_queue_name</tt> - The name of the queue used with <tt>deliver_later</tt>
   class Base < AbstractController::Base
     include DeliveryMethods
     include Previews

actionmailer/lib/action_mailer/delivery_job.rb

@@ -4,7 +4,7 @@ module ActionMailer
   # The <tt>ActionMailer::DeliveryJob</tt> class is used when you
   # want to send emails outside of the request-response cycle.
   class DeliveryJob < ActiveJob::Base # :nodoc:
-    queue_as :mailers
+    queue_as { ActionMailer::Base.deliver_later_queue_name }
 
     def perform(mailer, mail_method, delivery_method, *args) #:nodoc:
       mailer.constantize.public_send(mail_method, *args).send(delivery_method)

actionmailer/lib/action_mailer/delivery_methods.rb

@@ -16,6 +16,9 @@ module DeliveryMethods
       cattr_accessor :perform_deliveries
       self.perform_deliveries = true
 
+      cattr_accessor :deliver_later_queue_name
+      self.deliver_later_queue_name = :mailers
+
       self.delivery_methods = {}.freeze
       self.delivery_method  = :smtp
 

actionmailer/test/message_delivery_test.rb

@@ -11,6 +11,8 @@ class MessageDeliveryTest < ActiveSupport::TestCase
   setup do
     @previous_logger = ActiveJob::Base.logger
     @previous_delivery_method = ActionMailer::Base.delivery_method
+    @previous_deliver_later_queue_name = ActionMailer::Base.deliver_later_queue_name
+    ActionMailer::Base.deliver_later_queue_name = :test_queue
     ActionMailer::Base.delivery_method = :test
     ActiveJob::Base.logger = Logger.new(nil)
     @mail = DelayedMailer.test_message(1, 2, 3)
@@ -22,6 +24,7 @@ class MessageDeliveryTest < ActiveSupport::TestCase
   teardown do
     ActiveJob::Base.logger = @previous_logger
     ActionMailer::Base.delivery_method = @previous_delivery_method
+    ActionMailer::Base.deliver_later_queue_name = @previous_deliver_later_queue_name
   end
 
   test 'should have a message' do
@@ -82,4 +85,15 @@ def test_should_enqueue_and_run_correctly_in_activejob
     end
   end
 
+  test 'should enqueue the job on the correct queue' do
+    assert_performed_with(job: ActionMailer::DeliveryJob, args: ['DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], queue: "test_queue") do
+      @mail.deliver_later
+    end
+  end
+
+  test 'can override the queue when enqueuing mail' do
+    assert_performed_with(job: ActionMailer::DeliveryJob, args: ['DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], queue: "another_queue") do
+      @mail.deliver_later(queue: :another_queue)
+    end
+  end
 end

railties/test/application/configuration_test.rb

@@ -732,6 +732,19 @@ def index
       assert_equal [::MyMailObserver, ::MyOtherMailObserver], ::Mail.send(:class_variable_get, "@@delivery_notification_observers")
     end
 
+    test "allows setting the queue name for the ActionMailer::DeliveryJob" do
+      add_to_config <<-RUBY
+        config.action_mailer.deliver_later_queue_name = 'test_default'
+      RUBY
+
+      require "#{app_path}/config/environment"
+      require "mail"
+
+      _ = ActionMailer::Base
+
+      assert_equal 'test_default', ActionMailer::Base.send(:class_variable_get, "@@deliver_later_queue_name")
+    end
+
     test "valid timezone is setup correctly" do
       add_to_config <<-RUBY
         config.root = "#{app_path}"