I really like vttest. I used to use it when I was still working on Console Telnet for Win32 (https://github.com/cout/consoletelnet). It revealed a lot of bugs in how escape sequences were handled that I might never have noticed since they were obscure (yet important) corner cases.
I've (edited and) compiled VTTEST to run under Windows. The latest iteration of the Command Prompt does surprisingly well in the tests. Of course the new Windows Terminal does well too.
Vttest: https://invisible-island.net/vttest/