Merge branch 'mr-diff-discussion-deletion' into 'master'

Fixes diff discussions not being fully removed

Closes #53317

See merge request gitlab-org/gitlab-ce!22680

app/assets/javascripts/diffs/components/app.vue

@@ -153,13 +153,9 @@ export default {
     },
     setDiscussions() {
       if (this.isNotesFetched && !this.assignedDiscussions && !this.isLoading) {
-        requestIdleCallback(
-          () =>
-            this.assignDiscussionsToDiff().then(() => {
-              this.assignedDiscussions = true;
-            }),
-          { timeout: 1000 },
-        );
+        this.assignedDiscussions = true;
+
+        requestIdleCallback(() => this.assignDiscussionsToDiff(), { timeout: 1000 });
       }
     },
     adjustView() {

app/assets/javascripts/diffs/store/mutations.js

@@ -133,7 +133,7 @@ export default {
                 },
                 right: {
                   ...line.right,
-                  discussions: right ? line.right.discussions.concat(discussion) : [],
+                  discussions: right && !left ? line.right.discussions.concat(discussion) : [],
                 },
               };
             }

spec/javascripts/diffs/store/mutations_spec.js

@@ -221,6 +221,7 @@ describe('DiffsStoreMutations', () => {
 
       expect(state.diffFiles[0].parallelDiffLines[0].left.discussions.length).toEqual(1);
       expect(state.diffFiles[0].parallelDiffLines[0].left.discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0].parallelDiffLines[0].right.discussions).toEqual([]);
 
       expect(state.diffFiles[0].highlightedDiffLines[0].discussions.length).toEqual(1);
       expect(state.diffFiles[0].highlightedDiffLines[0].discussions[0].id).toEqual(1);