Turns out we were overthinking this one; as we already replace the entire method body with assertThrows, there are then no exception left to be thrown that are not already caught.

I'm just thinking with the above, what if the method throws multiple checked exceptions, and assertThrows only catches one, even if it is wrapping the entire method body. I think in that case, the remaining checked exception are still valid, or still not? From my memory I remember only removing one checked exception from the method signature, and keeping one when doing the junit 4 to 5 migration, where there were multiple checked exceptions.