Yes! Your testers can be whomever you like. However, be sure to pick people who you think will follow your instructions for testing the game and then give you honest feedback about what they thought of your game. If you have friends whom you trust, then they would be excellent people to playtest your game. But if you think your friends might take charge of your testing session or tell you only what they think you want to hear, then maybe you might want to ask some people who you don’t know as well, such as members of another patrol or some of your brother’s or sister’s friends.