Merge branch 'fix-commits-manual-merge' into 'master'

Fix bug where manually merged branches in a MR would end up with an empty diff

This bug manifested in 8.1 with the refactoring of `RefreshService`. Here's what happens:

1. User create a new branch `foo`.
2. User creates a merge request for `foo`.
3. User merges `foo` into `master` by hand.
4. `RefreshService` reloads the merge request. Since `master` is equivalent to `foo`, this results in an empty diff.
5. `RefreshService` then closes the MR.

This wasn't an issue when you use the normal "Accept Merge Request" flow because the act of clicking the button closes the merge request, so step 4 never happens.

Closes #3314

See merge request !1758

1 files changed, 19 insertions, 0 deletions

diff --git a/spec/services/merge_requests/refresh_service_spec.rb b/spec/services/merge_requests/refresh_service_spec.rb
index 227ac995ec2..7ee4488521d 100644
--- a/spec/services/merge_requests/refresh_service_spec.rb
+++ b/spec/services/merge_requests/refresh_service_spec.rb
@@ -62,6 +62,25 @@ describe MergeRequests::RefreshService do
       it { expect(@fork_merge_request.notes.last.note).to include('changed to merged') }
     end
 
+    context 'manual merge of source branch' do
+      before do
+        # Merge master -> feature branch
+        author = { email: 'test@gitlab.com', time: Time.now, name: "Me" }
+        commit_options = { message: 'Test message', committer: author, author: author }
+        master_commit = @project.repository.commit('master')
+        @project.repository.merge(@user, master_commit.id, 'feature', commit_options)
+        commit = @project.repository.commit('feature')
+        service.new(@project, @user).execute(@oldrev, commit.id, 'refs/heads/feature')
+        reload_mrs
+      end
+
+      it { expect(@merge_request.notes.last.note).to include('changed to merged') }
+      it { expect(@merge_request).to be_merged }
+      it { expect(@merge_request.diffs.length).to be > 0 }
+      it { expect(@fork_merge_request).to be_merged }
+      it { expect(@fork_merge_request.notes.last.note).to include('changed to merged') }
+    end
+
     context 'push to fork repo source branch' do
       let(:refresh_service) { service.new(@fork_project, @user) }
       before do