UV-protective clothing?

I bought an REI-branded UPF 30 long-sleeve shirt. The label has no information about the fabric, so I emailed REI to ask what it's made from, what UV-protective material it contains, how many washes the protection can endure, and whether REI tests the UV-blocking or just takes the manufacturer's word for it. No response to two emails. This isn't what I expected from REI. Has anyone out there had a similar experience? Is there actually a way to test UPF? Thanks.