Fix resolved discussions not expanding on side by side view

app/views/discussions/_parallel_diff_discussion.html.haml

@@ -4,7 +4,7 @@
     %td.notes_line.old
     %td.notes_content.parallel.old
       .content{ class: ('hide' unless discussions_left.any?(&:expanded?)) }
-        = render partial: "discussions/notes", collection: discussions_left, as: :discussion, line_type: 'old'
+        = render partial: "discussions/notes", collection: discussions_left, as: :discussion, line_type: 'old', locals: { disable_collapse_class: true }
   - else
     %td.notes_line.old= ("")
     %td.notes_content.parallel.old
@@ -14,7 +14,7 @@
     %td.notes_line.new
     %td.notes_content.parallel.new
       .content{ class: ('hide' unless discussions_right.any?(&:expanded?)) }
-        = render partial: "discussions/notes", collection: discussions_right, as: :discussion, line_type: 'new'
+        = render partial: "discussions/notes", collection: discussions_right, as: :discussion, line_type: 'new', locals: { disable_collapse_class: true }
   - else
     %td.notes_line.new= ("")
     %td.notes_content.parallel.new

changelogs/unreleased/fix-resolved-side-by-side.yml

+---
+title: Fix resolved discussions not expanding on side by side view
+merge_request:
+author:
+type: fixed

spec/features/merge_requests/diff_notes_resolve_spec.rb

@@ -97,6 +97,7 @@ feature 'Diff notes resolve', :js do
           visit_merge_request
         end
 
+        describe 'timeline view' do
           it 'hides when resolve discussion is clicked' do
             expect(page).to have_selector('.discussion-body', visible: false)
           end
@@ -108,6 +109,24 @@ feature 'Diff notes resolve', :js do
           end
         end
 
+        describe 'side-by-side view' do
+          before do
+            page.within('.merge-request-tabs') { click_link 'Changes' }
+            page.find('#parallel-diff-btn').click
+          end
+
+          it 'hides when resolve discussion is clicked' do
+            expect(page).to have_selector('.diffs .diff-file .notes_holder', visible: false)
+          end
+
+          it 'shows resolved discussion when toggled' do
+            find('.diff-comment-avatar-holders').click
+
+            expect(find('.diffs .diff-file .notes_holder')).to be_visible
+          end
+        end
+      end
+
       it 'allows user to resolve from reply form without a comment' do
         page.within '.diff-content' do
           click_button 'Reply...'