so pulled by dash out to repair some wiring issues...and dont want to do it again... how can i test the switch ans solenoid before I reinstall....??

The wire in the solenoid is already iffiy.... who sells these..??

Blow through the hose with your mouth to make sure it is open. Apply current to the green wire. Making sure to ground the solenoid to make a complete circuit. Listen for a "click" in the solenoid. Blow into the hose to see if it blocked off the air flow. I hope I have it the correct direction.

P.G. Classic Reproduction

Be careful of reproduction switches out currently. Have two friend who put air grabber on their cars and went through crap trying to find ones that worked properly. One guy had 6 repro ones all fail til he got a nos one and it worked perfectly.

Any way to test the switch?

I use a hand pump and two vacuum gauges.
All switches leak you want one that leaks the least.
Most of the time the nubs on the back are broken. They can be repaired. The aftermarket switches look good but don't have the quality like the originals. Most of them don't work properly. If you have one that does but the nubs get broken it can be repaired.

In this video the first switch as a vacuum leak at the nubs that is quite large.
The second switch has a leak but it is much less, repaired nubs.

https://youtu.be/oCmqnw0Y6Fg