Below is from the Princess web site:
We strongly recommend all guests take a viral COVID-19 test (PCR or antigen) prior to leaving home to avoid queues and travel disruptions associated with a possible positive test result on the day of embarkation.
We understand that it may be difficult for some of our guests to find testing that can provide results within a 2-day turnaround. Accordingly, for guests who did not receive their test results within 2 days prior to their embarkation, we are working to set up mobile testing sites near our embarkation ports to conduct COVID-19 testing the day before, or day of, your cruise departure.
The company providing the testing will charge a per-person fee (to be established; please check back on this page). Providers will not accept insurance, but you will be provided a receipt should you wish to submit the cost to your insurance carrier. Please consider this as a back-up alternative should you not be able to make arrangements prior to leaving home.
In accordance with CDC protocols, guests who test positive for COVID-19 on embarkation day will be denied boarding, together with their family members and close contacts, may be required to quarantine shoreside, and may be restricted from commercial air travel. If you, your family members, traveling companions or other close contacts are suspected of having COVID-19 and are denied boarding, you will be entitled to a 100% Future Cruise Credit.