alt Hacker Newsbecause even supposing you have an interface for your thing under test (which you don't necessarily, nor do you necessarily want to have to) it lets you skip over having to do any fake implementations, have loads of variations of said fake implementations, have that code live somewhere, etc etc.
Instead your mocks are all just inline in the test code: ephemeral, basically declarative therefore readily readable & grokable without too much diversion, and easily changed.
A really good usecase for Java's 'Reflection' feature.
An anonymous inner class is also ephemeral, declarative, inline, capable of extending as well as implementing, and readily readable. What it isn't is terse.
Mocking's killer feature is the ability to partially implement/extend by having some default that makes some sense in a testing situation and is easily instantiable without calling a super constructor.
Magicmock in python is the single best mocking library though, too many times have I really wanted mockito to also default to returning a mock instead of null.