how to update an entity with spring data jpa

Question

I have an entity and a Junit, I want to test that update method is working fine, but when I invoke save method from CrudRepository I get a new entry in my table instead of the u

Answer 1

The problem is in your updatePerson method in your service class. Specifically:

return personRepository.save(oldPerson);

All you are currently doing is saving a Person. That's why it is creating a second entry.
What you should do is find the oldPerson first,

Person p = personRepository.findOne(oldPerson.getId())

then update its attributes, and then save it like you did before. Hope that helps.