I am trying out a simple test case, But I get an exception java.lang.IllegalArgumentException: Entity not managed. Can somebody give me a test case to test how the refresh() of entitymanager works

//get username
User user = ObjectManager.findById(2L);
//make dirty
user.setUsername("xyz");
//undo dirty changes
ObjectManager.refresh(user);
assertEquals(eventLog.getUsername(), "john");


Also for the contains() method of the entityManager. It always returns false. I have tried getReference() and then check using contains() but again false.

Apparently your ObjectManager object is'nt a instance of entitymanager.
So can you please tell something more about your implementation of ObjectManager,
especially how the methods .findById() and .refresh() are implemented ?