Testing rear brake switch

[Johnnieye]

Can someone tell me how I would test this. It's the rear brake switch that screws into the master cylinder. I was able to solder the wires back together. Does it work on fluid pressure ?

 

[KaptinAmerika]

Yes it is a pressure switch
If you install it, bleed the brakes and then use an ohmmeter to test for continuity across the pins when you apply the brake pedal.
No continuity then the switch is bad