A typical driving test considers basic skills: Can you parallel park? Do you merge safely? Do you know to yield to pedestrians? No such government exam is required for cars driven by a computer. The idea has been dismissed by federal officials who oppose regulation and industry leaders who say they need freedom from rules to innovate. But a new study by the Rand Corp., funded by Uber's autonomous vehicle division and released Thursday, tries to map out what independent tests of driverless safety might look like and how they might be implemented.