I mostly play in tournaments at a local store. Since I'm still new to the game, I'm just meeting people and don't have any friends who already play the game, so I don't really have a "sparring partner" to try out new decks with before taking them to the tournies.

Other than the obvious of trying out two of my decks against each other in a solo game at home to see how well they play, what else does everyone do to "test" decks and see how well they work before taking them to a tourney?

If you don't have a friend to play with, Table Top Simulator on Steam is a really good way to try out/test decks. All you have to do is download Steam, and then it costs $20 to get the Table Top Simulator that you can play Star Wars Destiny on. It is a one time payment, not a monthly payment.

Ask the people you meet during those monthly tourneys. Perhaps they have a weekly playnight or are interested in one.

If you’re interested in grinding out lots and lots of games, Table Top Simulator is probably your best bet.