Two standard hose barbs, and a pressure gauge. A bicycle pump is what I used to pressurize the system.
So, this tested the whole system, except the tanks, which I have already tested.
I tested the fuel system plumbing with air pressure, and sprayed
soapy water on the outside to look for bubbles. I found
that almost every single AN connector leaked. Once I
got those fixed, I pressurized the system to about
50-60 psi, and then took periodic measurements over
the next week or so to watch it leak down. It never
got below about 20psi, IIRC, so I claimed victory.