Diesel Power had an article either this month or the last month that detailed the smog testing procedures that will be used. They also had a number of tips on how to pass the test.
According to the article, they will use a "smoke opacity test", which is a mechanized test that checks how much light passes through the exhaust at a certain rpm. So not just a visual inspection by a tech.
It certainly didn't sound like the end of the world, since most trucks should be able to pass. Kind of a bummer about the cost of the test though.