Washington Huskies will give USC's Sam Darnold his biggest test to date

USC Trojans quarterback Sam Darnold connects with JuJu Smith-Schuster (not shown) for a touchdown during the second half at the Los Angeles Memorial Coliseum in Los Angeles, CA on Saturday, September 10, 2016. (Photo by Ed Crisostomo/SCNG, file)For the first two months this season, USC coach Clay Helton had a habit.

When he watched film of the Trojans’ upcoming Pac-12 Conference opponent, he liked to view the footage from its game against Washington.

It was, Helton reasoned, because of similarities between the Trojans and Huskies.

After a practice this week, he drew parallels.

The teams often lined up in the same offensive formations. Their personnel mirrored each other, with ankle-breaking…