Disable deliver_later patch introduced in rails 5

- See rails/rails#24457 and rails/rails#26916

lib/extensions/action_mailer_suppression.rb

@@ -0,0 +1,2 @@
+# frozen_string_literal: true
+module Extensions::ActionMailerSuppression; end

lib/extensions/action_mailer_suppression/action_mailer.rb

@@ -0,0 +1,2 @@
+# frozen_string_literal: true
+module Extensions::ActionMailerSuppression::ActionMailer; end

lib/extensions/action_mailer_suppression/action_mailer/message_delivery.rb

@@ -0,0 +1,15 @@
+# This extension disables the check introduced in rails/rails#24457, which disables the
+# accessing or mutation of the +MessageDelivery+ object through raising an exception.
+#
+# Since Coursemology uses mailing templates (see #mail in +ActivityMailer+), this
+# extension reverses that patch.
+#
+# See rails/rails#26916 for potential progress / discussions on this issue,
+# or consider building a custom ActiveJob instead of #deliver_later.
+module Extensions::ActionMailerSuppression::ActionMailer::MessageDelivery
+  module PrependMethods
+    def processed?
+      false
+    end
+  end
+end

spec/notifiers/course/announcement_notifier_spec.rb

@@ -7,7 +7,7 @@
   with_tenant(:instance) do
     describe '#new_announcement' do
       let(:course) { create(:course) }
-      let(:user) { create(:course_user, course: course).user }
+      let!(:user) { create(:course_user, course: course).user }
       let(:announcement) { create(:course_announcement, course: course) }
 
       before do

spec/notifiers/course/assessment_notifier_spec.rb

@@ -10,9 +10,9 @@
     end
 
     describe '#assessment_attempted' do
-      let(:course) { create(:course) }
-      let(:assessment) { create(:assessment, course: course) }
-      let(:user) { create(:course_user, course: course).user }
+      let!(:course) { create(:course) }
+      let!(:assessment) { create(:assessment, course: course) }
+      let!(:user) { create(:course_user, course: course).user }
 
       subject { Course::AssessmentNotifier.assessment_attempted(user, assessment) }
 
@@ -23,9 +23,9 @@
 
     describe '#assessment_submitted' do
       let(:course) { create(:course) }
-      let(:course_user) { create(:course_user, course: course) }
+      let!(:course_user) { create(:course_user, course: course) }
       let(:user) { course_user.user }
-      let(:submission) { create(:submission, course: course, creator: user) }
+      let!(:submission) { create(:submission, course: course, creator: user) }
 
       subject { Course::AssessmentNotifier.assessment_submitted(user, course_user, submission) }
 
@@ -66,8 +66,8 @@
 
     describe '#assessment_opening' do
       let(:course) { create(:course) }
-      let(:assessment) { create(:course_assessment_assessment, course: course) }
-      let(:user) { create(:course_user, course: course).user }
+      let!(:assessment) { create(:course_assessment_assessment, course: course) }
+      let!(:user) { create(:course_user, course: course).user }
 
       subject { Course::AssessmentNotifier.assessment_opening(user, assessment) }
 

spec/notifiers/course/video_notifier_spec.rb

@@ -7,8 +7,8 @@
   with_tenant(:instance) do
     describe '#video_attempted' do
       let(:course) { create(:course) }
-      let(:video) { create(:video, course: course) }
-      let(:user) { create(:course_user, course: course).user }
+      let!(:video) { create(:video, course: course) }
+      let!(:user) { create(:course_user, course: course).user }
 
       subject { Course::VideoNotifier.video_attempted(user, video) }
 
@@ -19,8 +19,8 @@
 
     describe '#video_opening' do
       let(:course) { create(:course) }
-      let(:video) { create(:course_video, course: course) }
-      let(:user) { create(:course_user, course: course).user }
+      let!(:video) { create(:course_video, course: course) }
+      let!(:user) { create(:course_user, course: course).user }
       let(:activity) { Activity.find_by(object: video, event: :opening, actor: user) }
 
       subject { Course::VideoNotifier.video_opening(user, video) }
@@ -44,7 +44,7 @@
       let(:activity) { Activity.find_by(object: video, event: :closing, actor: user) }
 
       let(:course) { create(:course) }
-      let(:video) { create(:course_video, course: course, end_at: now) }
+      let!(:video) { create(:course_video, course: course, end_at: now) }
       let(:user) { create(:course_manager, course: course).user }
       let!(:submitted_student) { create(:course_student, course: course) }
       let!(:unsubmitted_student) { create(:course_student, course: course) }