Marks pending tasks for an user as done when he edit a MR

app/services/merge_requests/update_service.rb

@@ -15,6 +15,10 @@ module MergeRequests
     end
 
     def handle_changes(merge_request, options = {})
+      if have_changes?(merge_request, options)
+        task_service.mark_as_done(merge_request, current_user)
+      end
+
       if merge_request.previous_changes.include?('target_branch')
         create_branch_change_note(merge_request, 'target',
                                   merge_request.previous_changes['target_branch'].first,
@@ -44,5 +48,22 @@ module MergeRequests
     def close_service
       MergeRequests::CloseService
     end
+
+    private
+
+    def have_changes?(merge_request, options = {})
+      valid_attrs = [:title, :description, :assignee_id, :milestone_id, :target_branch]
+
+      attrs_changed = valid_attrs.any? do |attr|
+        merge_request.previous_changes.include?(attr.to_s)
+      end
+
+      old_labels = options[:old_labels]
+      labels_changed = old_labels && merge_request.labels != old_labels
+
+      if attrs_changed || labels_changed
+        task_service.mark_as_done(merge_request, current_user)
+      end
+    end
   end
 end

spec/services/merge_requests/update_service_spec.rb

@@ -103,11 +103,35 @@ describe MergeRequests::UpdateService, services: true do
         create(:pending_assigned_task, user: user, project: project, target: merge_request, author: user2)
       end
 
+      context 'when the title change' do
+        before do
+          update_merge_request({ title: 'New title' })
+        end
+
+        it 'marks pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+      end
+
+      context 'when the description change' do
+        before do
+          update_merge_request({ description: 'Also please fix' })
+        end
+
+        it 'marks pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+      end
+
       context 'when is reassigned' do
         before do
           update_merge_request({ assignee: user2 })
         end
 
+        it 'marks previous assignee pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+
         it 'creates a pending task for new assignee' do
           attributes = {
             project: project,
@@ -121,6 +145,36 @@ describe MergeRequests::UpdateService, services: true do
           expect(Task.where(attributes).count).to eq 1
         end
       end
+
+      context 'when the milestone change' do
+        before do
+          update_merge_request({ milestone: create(:milestone) })
+        end
+
+        it 'marks pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+      end
+
+      context 'when the labels change' do
+        before do
+          update_merge_request({ label_ids: [label.id] })
+        end
+
+        it 'marks pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+      end
+
+      context 'when the target branch change' do
+        before do
+          update_merge_request({ target_branch: 'target' })
+        end
+
+        it 'marks pending tasks as done' do
+          expect(pending_task.reload).to be_done
+        end
+      end
     end
 
     context 'when MergeRequest has tasks' do
@@ -155,6 +209,5 @@ describe MergeRequests::UpdateService, services: true do
         end
       end
     end
-
   end
 end