That thing can be discussed. What about demo or free money then? They also give chance to test any game on a platform. They even give more chances to test any game. Lets take BetFury for example - you get 42 sat hourly. Minimum bet is 1 sat in casual games, slots usually ask 1 cent for a spin, which is more than 1 sat, and blackjack ask 10 cents for example. So I would not call faucet as something you use to test games. It is more like a way to hold customers imho.