Thanks for the code, that helped… I was able to reproduce the issue you’re seeing.
I would first decide if you need the @EnableProcessApplication annotation. More here. If you do, this post from the thread I linked is applicable. Adding the config class and removing @EnableProcessApplication from your DemoApplication should do the trick (keeping your test class as written).
If you don’t need the annotation, I would just remove it. We already know your @DataJpaTest test works fine with it removed.