Yes, you're right, I've used the the underscore here to mark different test cases for tests of one and the same method. I'll change it so we use camel case consistently.

Regarding using only underscores, I'm a bit undecided. As you say it can improve readability (which is why I used it here), but I think it would feel a bit strange (un-Java-ish) if we only used that style.

Personally I wouldn't mind using undercores only in selected specific cases, but I think for now it might be better to use one style so we can later on decide what approach to pursue.