well, the tests need to be contained in their own address space for proper testing, to guarantee that the runner can properly finish in anything happens inside the test
Unit testing framework that focus embedded testing sacrifice usability for portability
So yes, for very specific hardware tests, you'd be better of making a bridge from the test runner to the chip, or use a separate test suite for hardware tests
I'll open an issue to see what can be done about that. Feel free to tell any suggestions you have! It's users like you that makes the project even more awesome day after day :)