> I regularly write static methods and test them with JUnit
Implementing mock objects which return "unexpected" results is impossible with static methods.
The standard 1 interface + 1 impl pattern in Java is just so that the Proxy.newProxyInstance can create a decorated or mocked object for testing.
So you can test the methods directly, but you can't write failure-inducing methods (like a connect exception throwing one) which test the methods which use it.
