The lights can be opened manually by hand or with the vacuum switch.
I can't remember if the '80 has this or not, but earlier C3s have three
controls under the steering column. The outside two are pull down, push up
vacuum switches. One opens the wiper tray door (1968-1972) and the other
opens the headlights. In '80, there may be one. I don't have one on my '79
but I think someone has changed it. It was included because Chevy advised
opening them and leaving them in icy winter conditions.
If that doesn't work, you can reach under the nose and push the lights up.
They have a knee-like hinge that locks into the open position. this has to
be pulled forward to close them manually by hand.
Chevrolet in the early C3 owner's manuals advised how to do this in event of
vacuum actuation failure. Lack of this feature does not make the car
unroadworthy, just harder to use, especially if you are in good pants.
Check for vacuum lines off. You will find them at each headlight pod, a
vacuum switch in between the headlights under the nose panel, connected to
the front bumper torque tube (doubles as a vacuum reservoir), and then back
under the dash. There is a check vlave at the intake manifold that looks
like a flying saucer with either one tube out top and bottom or one tube out
the top and two out the bottom.
Last is like nospam said. Pull (and plug) the vacuum lines off the
headlight pods, then open them by hand. They will stay open and you can
pass your test.