Absolutely write single-function unit tests, if the function has clearly defined inputs and outputs but a tricky implementation. A lot of business rules work th

Absolutely write single-function unit tests, if the function has clearly defined inputs and outputs but a tricky implementation. A lot of business rules work this way, so if you have a "functional core, imperative shell" line-of-business application with unclear or changing requirements, unit tests will be your best friend for getting the details right. But testing each class in the project with a Mockito-encrusted setup featuring cardboard bananas/gorillas/jungles—best practice in Java-land—seems tedious, and tedium is the enemy of a good testing strategy because programmers won't follow it. They'll bodge in a solution, get their teammates to lgtm it, and roll it out under the slightest bit of deadline pressure.