Negative test to enter Spain?

Testing is only required for the non-vaccinated.
I just got back. Before departure, I filled out the form here: https://www.sanidad.gob.es/en/profesionales/saludPublica/ccayes/alertasActual/nCov/spth.htm
I received a QR code that I uploaded to my airline, along with my passport and vaccination card, to get my boarding pass--easy peasy. If I recall correctly, the QR code was also verified upon arrival (but in my sleep-deprived state I may not remember correctly).

Two family members and I returned from Barcelona, Spain, yesterday (Tues. 7 June). As we read the requirements to enter Spain 2 weeks ago, it did not seem clear whether our US vaccination (and booster) cards would be accepted. So to be sure, we scheduled rapid result Covid testing within the 72 hours prior to departure and uploaded that info into the Spanish government form, and then received the QR code. Allow time to fill out the form, especially if you are somewhat electronically challenged. Yes, it was checked both at JFK and upon arrival in Madrid‘s Barajas Airport.
Within the twenty-four hours before we left Barcelona, we did the antigen test required to enter the US —and, although we loved Spain, are thankful all were negative and could fly home as scheduled. The testing information had to go on the US entry form (we put it on the American Airlines app) and was checked by the airline at the Barcelona airport before we were authorized. to fly. The testing site near the Sagrada Familia church was very easy to find and the personnel welcoming and multilingual. Cost was 23 euros each.

No test needed for fully vaccinated people. Simply fill out the Spain Travel Health Form. You’ll receive a QR code. When we arrived in Madrid, the QR code was checked right after passing through immigration and we were on our way. In Spain, nobody ever asked to see our CDC cards. As already stated, the CDC card was uploaded to the airline. We returned on June 6th.