The "Microsoft Extensible Emulator" is part of the Visual Studio IDE AFAIK. But it is great in allowing you to mimick your end device when you still don't have hardware (I have a design but I am testing some concepts).
The MAX7219 emulator code I wrote myself because I wanted to see the state of the chip during debugging (just as if I had a real emulator pOD on a real device) but I have to fix it based on your comments (the NoOp). However, it goes only as far as keeping track of the register values, state and notifying the UI to update the UI accordingly. It does not include a real 7-segment emulator that would ideally read the status of the A-G,DP segment output pins and display accordingly. Perhaps some day I add it, in the meantimeI have to fix the emulator code and find some suppliers for my 7-segment displays