What about interpretations of quantum mechanics? I'd argue these are scientific, but nobody has any idea how to test them just yet.
They might do one day.
But if we weren't willing to talk about them before they were testable then nobody would be inspired to develop the necessary tests.
The fact that they're an essential part of the scientific process makes them science as far as I'm concerned. If it helps make up your mind, plenty of people called scientists spend time thinking about them.
There are lots of tests for quantum mechanics, it’s probably the most rigorously tested theory in physics.
Some parts of quantum theories are inferred, but they’re inferred from data collected in reproducible tests. Also, any part of quantum theory that hasn’t been confirmed by experiment has scientists working to do just that. If something was untestable and thought to never be testable in the future, then it wouldn’t be considered science.
If you make a prediction that by its nature cannot be tested, you really can't do anything useful with it.