fix exercise#duplicate when xml_id_path is set

Author: kkoehn

app/controllers/exercises_controller.rb

@@ -56,7 +56,7 @@ def batch_update
   end
 
   def clone
-    exercise = @exercise.duplicate(public: false, token: nil, user: current_user)
+    exercise = @exercise.duplicate(public: false, token: nil, user: current_user, uuid: nil)
     exercise.send(:generate_token)
     if exercise.save
       redirect_to(exercise_path(exercise), notice: t('shared.object_cloned', model: Exercise.model_name.human))

spec/controllers/exercises_controller_spec.rb

@@ -49,6 +49,15 @@
       expect_redirect(Exercise.last)
     end
 
+    context 'when exercise has uuid' do
+      let(:exercise) { create(:dummy, uuid: SecureRandom.hex) }
+
+      it 'clones the exercise' do
+        expect_any_instance_of(Exercise).to receive(:duplicate).with(hash_including(public: false, user:)).and_call_original
+        expect { perform_request.call }.to change(Exercise, :count).by(1)
+      end
+    end
+
     context 'when saving fails' do
       before do
         allow_any_instance_of(Exercise).to receive(:save).and_return(false)