It is my understanding that most other islands that have announced a plan so far have required a negative Covid 19 test no more than 2 or 3 days PRIOR to the flight. Therefore the cost of the test and the consequences, if the person tests positive, would be borne in the person's country of origin. While this doesn't seem like a perfect plan either, because the person could go from negative to positive in two days, (or the test could plain be WRONG), it seems to make more sense than a plan to test AFTER people arrive.