The basic scenario is that the self-driving car's brakes fail, and pedestrians are ahead. You must decide between hitting that group of pedestrians or one of two other scenarios: for some, the other scenario is to swerve into a concrete wall; in the rest, the other scenario is a second group of pedestrians. The program varies the number, gender, age, and sometimes species of the parties that would be killed in the crash, but basically, at least one will die in any given scenario.
The program then analyzes your stance on the different variables. I took the test myself. Here are my results.
I feel kind of dirty now.