alt Hacker NewsMockito uses declarative matching style of specifying what should be mocked. You don't need to implement or even stub all of interface methods since Mockito can do it itself. It may be extremely concise. For example, interfaces may have tens methods or even more, but only one method is needed (say, java.sql.ResultSet). And finally probably the most important thing, interaction with mocks is recorded and then can be verified if certain methods were invoked with certain arguments.
That’s the seductive power of mocking - you get a test up and running quickly. The benefit to the initial test writer is significant.
The cost is the pain - sometimes nightmarish - for other contributors to the code base since tests depending on mocking are far more brittle.
Someone changes code to check if the ResultSet is empty before further processing and a large number of your mock based tests break as the original test author will only have mocked enough of the class to support the current implementation.
Working on a 10+ year old code base, making a small simple safe change and then seeing a bunch of unit tests fail, my reaction is always “please let the failing tests not rely on mocks”.