For testing I use an open-source program called Cockatrice (search google/github for it). It comes with a utility that can scrape the official wizards card db a

For testing I use an open-source program called Cockatrice (search google/github for it). It comes with a utility that can scrape the official wizards card db and then can connect to a multiplayer server. It doesn't support rules enforcement (it's a virtual tabletop), but it does work on Windows/Mac/Linux and gets out of your way enough to be excellent at testing with friends (particularly friends who may not live near you). Add in a voice chat client, and it's actually faster than playing with physical cards (shuffling is faster due to the computer doing it).