Henning Makholm wrote:
A program in main must not only be able to run and avoid crashing without non-free (or hypothetical) support data; it must also at least be able to perform to a reasonable degree whatever is its main practical function. A set of dummy data whose only practical function is to demonstrate that the software can run without crashing is not sufficient.
In the case of zsnes its practical function is to emulate a SNES console, with all its hardware. It supports this completely without any non-free data. It's only that most data for practical use is non-free.
Take Wine. It emulates the Windows API quite well to run Windows application. Now one could argue that most of them are non-free if you look at them from a DFSG point of view. And the calculator etc. they ship with Wine is also a set of dummy data which could calculate some very basic equations but which primarily demonstrate that it runs without crashing. (This is only from my limited knowledge back in the old days when I occasionally used it.)
Kind regards, Philipp Kern