National Security Agency chief Gen. Keith Alexander revealed Wednesday that his spy agency once tested whether it could track Americans' cellphone locations, in addition to its practice of sweeping broad information about calls made.Alexander and Director of National Intelligence James Clapper testified at a Senate Judiciary Committee hearing on proposed reforms to the NSA's surveillance of phone and internet usage around the world, exposed in June by former NSA analyst Edward Snowden. But neither spy chief discussed proposed reforms; instead they were questioned about new potential abuses that have come to light since then.