[joshvm]

Emulation works well if you have firmware and an emulator. For example, the Ardupilot autopilot software has both hardware-in-the-loop and software-in-the-loop packages which use the actual firmware. It runs off an STM32 emulator (I think) which is well defined. As you say, if you don't have that firmware, your emulator is only as good as your reverse engineering is.

When I'm testing thermal cameras there are a sequence of things I can check to ensure that the test worked: was the command sent without errors? Did I get an error back from the camera (e.g. CRC failure)? Does the state of the camera change as I expect it to? If all of those things are correct then the likelihood is that the command sent OK. Of course for states you should check various permutations (e.g. shutter open and shutter closed) to make sure that you don't have a bug in your state reading code :)

Here's a stereo matching example from OpenCV. This is a case when you do have the correct answer, but you don't expect to equal it, and your tolerance to accuracy varies with algorithm:

https://github.com/opencv/opencv/blob/055645080161c6af6083b6...