I'm currently writing a DataStore ModuleScript wrapper for the purpose of debugging without having to actually use DataStoreService, to avoid corrupting or losing data.
Currently, the only way I know to check for a Test Server is to test if the Players have a userId of -1. This won't work if there is no Player connected to the Server, however.
Is there a way, then, to determine if a Server is a Test Server without using a Player?

4 comments
game.PlaceId == 0 for a test server, I think
Yep, as wazap said.
Game:GetService("TestService") ?
very late, but for future explorers, if game.JobId returns an empty string, it's offline