I think rbanffy is referring to vttest[1], but I'm not certain.

[1]: https://www.invisible-island.net/vttest/

EDIT to add: vttest is maintained by the current maintainer of xterm. It's the "torturiest" VT test I know of.

No. Not this one. It's too much work to test everything. A much more concise can be used from:

     curl -q http://www.ibiblio.org/pub/multimedia/animation/vt100-animation/torturetest.vt

On a real terminal, you'll be able to see even the smooth scrolling function that AFAIK no windowed terminal implements.

Whoa, thanks! It looks like I’ve got some reading to do.

Next steps would be supporting Tektronix and ReGIS graphics.

Sixel graphics are a terrible idea.