The French-side test centers, the one mentioned in the article and the Red Cross site in Hope Estate, are supposed to be available to tourists who are staying on the French side. PCR testing capacity is constrained due to a limited supply of reagents, and are preferred to be limited to suspected cases, contact cases, and pre-surgery testing. Antigen tests can be done at the site in Hope Estate between 11:30 and 2:00 on weekdays. I’m not sure about weekend hours. The last that I heard was that you should bring your passport (or Carte Vitale if you’re French) if you’re getting tested on the French side.

Much of the above is from today’s FB post by the Prefecture, the rest from island friends.