The tester they give is basically just a pulse oximeter that logs your heart rate and SpO2 all night. I'm not sure how they interpret it, but I'd imagine that if your heart rate goes crazy and your oxygen drops, that's probably bad.

Otherwise you can look at questionnaires that ask things like whether you wake up a lot at night or snore, etc.

That said... it's pretty easy to just get a device that they give you that you connect to your phone to log data for a night. And they know what they're doing when they interpret it. So I would recommend that, since it's really easy to just go to a place and get a device and do a test.

This isn't like it used to be where you'd have to sleep in some strange place.