When to use mock objects in unit tests

Question

I\'m aware that there are many questions about mocking and testing, but I didn\'t find any that helped me perfectly, so I still have problems understanding the follwing:

Answer 1

More often than not, mocking is used to replace actual calls that are hard to duplicate in testing. For instance, assume ProcessClass makes a REST call to retrieve Citizen information. For a simple unit test, it would be hard to duplicate this REST call. However, you can "mock" the RestTemplate and dictate the different types of returns to insure your code would handle the 200's, 403's, etc. Additionally you could change the type of information to then also test your code to insure that bad data is handled, like missing or null information.

In your case you can actually create a Citizen, and then test that the Citizen is an object in the list or that getByName returns the proper object. So mocking is not needed in this example.