Personally, I think the most important value for test cases is simplicity, so I’m definitely skeptical about support for something like this.
FWIW, about the first example specifically I would argue that you should not be writing assertions against test inputs since they are supposed to be known. Granted I’m not familiar with the DSL shown so maybe I’m misunderstanding something but generally I would only expect the second part of that assertion to be a meaningful test since the former would be testing the test itself.
