Guard with feature flag

app/services/merge_requests/refresh_service.rb

@@ -66,13 +66,18 @@ module MergeRequests
 
       return if merge_requests.empty?
 
+      commit_analyze_enabled = Feature.enabled?(:branch_push_merge_commit_analyze, @project, default_enabled: true)
+      if commit_analyze_enabled
         analyzer = Gitlab::BranchPushMergeCommitAnalyzer.new(
           @commits.reverse,
           relevant_commit_ids: merge_requests.map(&:diff_head_sha)
         )
+      end
 
       merge_requests.each do |merge_request|
+        if commit_analyze_enabled
           merge_request.merge_commit_sha = analyzer.get_merge_commit(merge_request.diff_head_sha)
+        end
 
         MergeRequests::PostMergeService
           .new(merge_request.target_project, @current_user)

spec/services/merge_requests/refresh_service_spec.rb

@@ -654,6 +654,11 @@ describe MergeRequests::RefreshService do
 
     subject { service.execute(oldrev, newrev, 'refs/heads/merge-commit-analyze-before') }
 
+    context 'feature enabled' do
+      before do
+        stub_feature_flags(branch_push_merge_commit_analyze: true)
+      end
+
       it "updates merge requests' merge_commits" do
         expect(Gitlab::BranchPushMergeCommitAnalyzer).to receive(:new).and_wrap_original do |original_method, commits|
           expect(commits.map(&:id)).to eq(%w{646ece5cfed840eca0a4feb21bcd6a81bb19bda3 29284d9bcc350bcae005872d0be6edd016e2efb5 5f82584f0a907f3b30cfce5bb8df371454a90051 8a994512e8c8f0dfcf22bb16df6e876be7a61036 689600b91aabec706e657e38ea706ece1ee8268f db46a1c5a5e474aa169b6cdb7a522d891bc4c5f9})
@@ -670,4 +675,23 @@ describe MergeRequests::RefreshService do
         expect(merge_request_side_branch.merge_commit.id).to eq('29284d9bcc350bcae005872d0be6edd016e2efb5')
       end
     end
+
+    context 'when feature is disabled' do
+      before do
+        stub_feature_flags(branch_push_merge_commit_analyze: false)
+      end
+
+      it "does not trigger analysis" do
+        expect(Gitlab::BranchPushMergeCommitAnalyzer).not_to receive(:new)
+
+        subject
+
+        merge_request.reload
+        merge_request_side_branch.reload
+
+        expect(merge_request.merge_commit).to eq(nil)
+        expect(merge_request_side_branch.merge_commit).to eq(nil)
+      end
+    end
+  end
 end