Add a spec for dupcalite merge request pipeline creation case

This is EE related change

ee/spec/services/ee/merge_requests/refresh_service_spec.rb

@@ -182,5 +182,46 @@ describe MergeRequests::RefreshService do
         end
       end
     end
+
+    describe 'Pipelines for merge requests' do
+      let(:service) { described_class.new(project, current_user) }
+      let(:current_user) { merge_request.author }
+
+      let(:config) do
+        {
+          test: {
+            stage: 'test',
+            script: 'echo',
+            only: ['merge_requests']
+          }
+        }
+      end
+
+      before do
+        project.add_developer(current_user)
+        project.update(merge_pipelines_enabled: true)
+        stub_licensed_features(merge_pipelines: true)
+        stub_ci_pipeline_yaml_file(YAML.dump(config))
+      end
+
+      it 'creates a merge request pipeline' do
+        expect { subject }
+          .to change { merge_request.pipelines_for_merge_request.count }.by(1)
+
+        expect(merge_request.all_pipelines.last).to be_merge_request_pipeline
+      end
+
+      context "when MergeRequestUpdateWorker is retried by an exception" do
+        it 'does not re-create a duplicate merge request pipeline' do
+          expect do
+            service.execute(oldrev, newrev, "refs/heads/#{source_branch}")
+          end.to change { merge_request.pipelines_for_merge_request.count }.by(1)
+
+          expect do
+            service.execute(oldrev, newrev, "refs/heads/#{source_branch}")
+          end.not_to change { merge_request.pipelines_for_merge_request.count }
+        end
+      end
+    end
   end
 end