Automatically update MR merge-ref along merge status

This couples the code that transitions the `MergeRequest#merge_status`
and refs/merge-requests/:iid/merge ref update.

In general, instead of directly telling `MergeToRefService` to update
the merge ref, we should rely on `MergeabilityCheckService` to keep
both the merge status and merge ref synced. Now, if the merge_status is
`can_be_merged` it means the merge-ref is also updated to the latest.

We've also updated the logic to be more systematic and less user-based.

1 files changed, 16 insertions, 0 deletions

diff --git a/spec/services/service_response_spec.rb b/spec/services/service_response_spec.rb
index 30bd4d6820b..e790d272e61 100644
--- a/spec/services/service_response_spec.rb
+++ b/spec/services/service_response_spec.rb
@@ -16,6 +16,13 @@ describe ServiceResponse do
       expect(response).to be_success
       expect(response.message).to eq('Good orange')
     end
+
+    it 'creates a successful response with payload' do
+      response = described_class.success(payload: { good: 'orange' })
+
+      expect(response).to be_success
+      expect(response.payload).to eq(good: 'orange')
+    end
   end
 
   describe '.error' do
@@ -33,6 +40,15 @@ describe ServiceResponse do
       expect(response.message).to eq('Bad apple')
       expect(response.http_status).to eq(400)
     end
+
+    it 'creates a failed response with payload' do
+      response = described_class.error(message: 'Bad apple',
+                                       payload: { bad: 'apple' })
+
+      expect(response).to be_error
+      expect(response.message).to eq('Bad apple')
+      expect(response.payload).to eq(bad: 'apple')
+    end
   end
 
   describe '#success?' do