Comparing the output of your system against an oracle is one property you can test.
But you don't always have an oracle. So other properties still make sense.
As a simple example: if you code up a quantum mechanics simulator, that's hard, and I wouldn't be able to code up an oracle for you straight away. But I can tell you that you probably want to check that things like momentum and energy better be conserved.
But you don't always have an oracle. So other properties still make sense.
As a simple example: if you code up a quantum mechanics simulator, that's hard, and I wouldn't be able to code up an oracle for you straight away. But I can tell you that you probably want to check that things like momentum and energy better be conserved.