[tveita]

I've definitely seen Opus go to town when asked to test a fairly simple builder. Possibly it inferred something about testing the "contract", and went on to test such properties as

  - none of the "final" fields have changed after calling each method
  - these two immutable objects we just confirmed differ on a property are not the same object

In addition to multiple tests with essentially identical code, multiple test classes with largely duplicated tests etc.