Can you go into more details on situations that would be hard to test? This has all only been a thought experiment for me so far, and in my thought experiment I

Can you go into more details on situations that would be hard to test? This has all only been a thought experiment for me so far, and in my thought experiment I handwave these sort of issues away by thinking "that's what emulation/simulation is for" – but I hadn't considered leading data via power use, so clearly I need to learn more there.