Allow Email Replies to Notes to Create Discussions

app/mailers/notify.rb

@@ -178,7 +178,7 @@ class Notify < ApplicationMailer
     headers['In-Reply-To'] = message_id(note.references.last)
     headers['References'] = note.references.map { |ref| message_id(ref) }
 
-    headers['X-GitLab-Discussion-ID'] = note.discussion.id if note.part_of_discussion?
+    headers['X-GitLab-Discussion-ID'] = note.discussion.id if note.part_of_discussion? || note.can_be_discussion_note?
 
     headers[:subject] = "Re: #{headers[:subject]}" if headers[:subject]
 

app/models/sent_notification.rb

@@ -48,7 +48,7 @@ class SentNotification < ApplicationRecord
     end
 
     def record_note(note, recipient_id, reply_key = self.reply_key, attrs = {})
-      attrs[:in_reply_to_discussion_id] = note.discussion_id if note.part_of_discussion?
+      attrs[:in_reply_to_discussion_id] = note.discussion_id if note.part_of_discussion? || note.can_be_discussion_note?
 
       record(note.noteable, recipient_id, reply_key, attrs)
     end

changelogs/unreleased/afontaine-make-discussions-from-emails.yml

+---
+title: Allow Email Replies to Notes to Create Discussions
+merge_request: 56711
+author:
+type: changed

ee/spec/lib/gitlab/email/handler/create_note_handler_spec.rb

@@ -23,9 +23,8 @@ RSpec.describe Gitlab::Email::Handler::CreateNoteHandler do
 
   context "when the note could not be saved" do
     before do
-      allow_next_instance_of(Note) do |instance|
-        allow(instance).to receive(:persisted?).and_return(false)
-      end
+      # https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56711#note_551958817
+      allow_any_instance_of(Note).to receive(:persisted?).and_return(false) # rubocop:disable RSpec/AnyInstanceOf
     end
 
     it "raises an InvalidNoteError" do

spec/lib/gitlab/email/handler/create_note_handler_spec.rb

@@ -59,7 +59,7 @@ RSpec.describe Gitlab::Email::Handler::CreateNoteHandler do
   end
 
   shared_examples 'a reply to existing comment' do
-    it 'creates a comment' do
+    it 'creates a discussion' do
       expect { receiver.execute }.to change { noteable.notes.count }.by(1)
       new_note = noteable.notes.last
 
@@ -68,11 +68,7 @@ RSpec.describe Gitlab::Email::Handler::CreateNoteHandler do
       expect(new_note.note).to include('I could not disagree more.')
       expect(new_note.in_reply_to?(note)).to be_truthy
 
-      if note.part_of_discussion?
       expect(new_note.discussion_id).to eq(note.discussion_id)
-      else
-        expect(new_note.discussion_id).not_to eq(note.discussion_id)
-      end
     end
   end
 

spec/models/sent_notification_spec.rb

@@ -72,8 +72,8 @@ RSpec.describe SentNotification do
 
       it_behaves_like 'a successful sent notification'
 
-      it 'does not set in_reply_to_discussion_id' do
-        expect(subject.in_reply_to_discussion_id).to be_nil
+      it 'sets in_reply_to_discussion_id' do
+        expect(subject.in_reply_to_discussion_id).to eq(note.discussion_id)
       end
     end
   end
@@ -212,10 +212,10 @@ RSpec.describe SentNotification do
 
       subject { described_class.record_note(note, note.author.id) }
 
-      it 'creates a comment on the issue' do
+      it 'converts the comment to a discussion on the issue' do
         new_note = subject.create_reply('Test')
         expect(new_note.in_reply_to?(note)).to be_truthy
-        expect(new_note.discussion_id).not_to eq(note.discussion_id)
+        expect(new_note.discussion_id).to eq(note.discussion_id)
       end
     end
 
@@ -247,10 +247,10 @@ RSpec.describe SentNotification do
 
       subject { described_class.record_note(note, note.author.id) }
 
-      it 'creates a comment on the merge request' do
+      it 'converts the comment to a discussion on the merge request' do
         new_note = subject.create_reply('Test')
         expect(new_note.in_reply_to?(note)).to be_truthy
-        expect(new_note.discussion_id).not_to eq(note.discussion_id)
+        expect(new_note.discussion_id).to eq(note.discussion_id)
       end
     end
 

spec/support/shared_contexts/email_shared_context.rb

@@ -185,6 +185,7 @@ RSpec.shared_examples :note_handler_shared_examples do |forwardable|
     let(:email_raw) { with_quick_actions }
 
     let!(:sent_notification) do
+      allow(Gitlab::ServiceDesk).to receive(:enabled?).with(project: project).and_return(true)
       SentNotification.record_note(note, support_bot.id, mail_key)
     end