The Test server uses the same account information as Live, except when they make special exceptions for things like testing booster packs. Once everything goes back to normal, you'll only have GR access on Test if you really have GR.
And if the Beta server is merged with Test (it probably won't be), it would become a normal Test server.
@Roderick
Is the GR server going to come down and be part of the Test server or are they going to be kept separate?
If I am unable to buy GR would I be able to test out those new power sets on the test server or is that going to require the GR serial too?