[zahlman]

>You want a program that takes in A and returns B within X milliseconds

No, I actually want a lot more than that. I just didn't communicate all of it, because I'm accustomed to you understanding what good software is. (Or I didn't hire you in the first place, because I don't trust others to care like I do.)

If the microwave doesn't cook my food well, I can probably adjust for it; and anyway the objective power metric isn't the thing that matters to me, but the temperature and taste of the food I pull out. The code is an entirely different story, assuming I'm actually asking for code and not a finished program. Because I'm going to have to integrate it into something else.

And yeah, like the sibling comment said, the currently existing tests aren't actually the full interface. And they, too, are code, which can be wrong.