Auto resolve new notes of resolved discussions

**Why?**

The previous behavior had resolved discussions being unresolved
when commented on. This was strange UX, especially since there
is a separate button for "Comment & unresolve discussion".

https://gitlab.com/gitlab-org/gitlab-ce/issues/24128

**Note:**

- Also adds changelog

1 files changed, 15 insertions, 0 deletions

diff --git a/spec/services/notes/build_service_spec.rb b/spec/services/notes/build_service_spec.rb
index 6e1c1fe6c02..ff85c261cd4 100644
--- a/spec/services/notes/build_service_spec.rb
+++ b/spec/services/notes/build_service_spec.rb
@@ -4,6 +4,8 @@ describe Notes::BuildService do
   let(:note) { create(:discussion_note_on_issue) }
   let(:project) { note.project }
   let(:author) { note.author }
+  let(:merge_request) { create(:merge_request, source_project: project) }
+  let(:mr_note) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project, author: author) }
 
   describe '#execute' do
     context 'when in_reply_to_discussion_id is specified' do
@@ -12,6 +14,19 @@ describe Notes::BuildService do
           new_note = described_class.new(project, author, note: 'Test', in_reply_to_discussion_id: note.discussion_id).execute
           expect(new_note).to be_valid
           expect(new_note.in_reply_to?(note)).to be_truthy
+          expect(new_note.resolved?).to be_falsey
+        end
+
+        context 'when discussion is resolved' do
+          before do
+            mr_note.resolve!(author)
+          end
+
+          it 'resolves the note' do
+            new_note = described_class.new(project, author, note: 'Test', in_reply_to_discussion_id: mr_note.discussion_id).execute
+            expect(new_note).to be_valid
+            expect(new_note.resolved?).to be_truthy
+          end
         end
       end