You can do a quick test at "Diagnostictest", Carrer de l'Hospital, 6 (it's practically a three minute walk from Orient Atiram Hotel).

You can go there without reservation, I recommend you to go early in the morning (it opens at 8.00 am) to avoid waiting. It takes about half an hour to get the result, but you can drop by anytime during the day (closing time is 9 pm).

The rapid antigenic test costs 30 euros.