OMP working or not ?
 

This may be a dumb question but how do I know if my OMP is working properly ? Is there a simple procedural test that can be performed etc. ?

If on the stock ecu, it would put the car in limp mode iirc.
if on Power FC, you can check that in the Sensor area.

With any luck, the FSM hopefully has troubleshooting / verification procedures but hopefully another forum member will chime in on that shortly. Thankfully, I've never needed to check that beyond what the Power FC provides. :)

the old cars had you detach the lines and with a stop watch measure how much oil you get at like 2000rpm or whatever it is.
the 12A cars are like 6cc in 6 minutes, and a cc is like a drop. FD is about half of that.

its kind of tricky to measure there is so little oil

As mentioned, on the STOCK ECU there’s not one but three codes related to the OMP… any one of which will put you into limp. You’d know that immediately and I don’t think any other system is as closely monitored via the ECU.
On the PFC you can go to the sensor check screen. I assume the other standalones have something similar.
The above gives me assurance that the pump is working as designed. To make sure that oil is actually being delivered to the housings I think the only practical way is to look for any signs of leakage on top of the engine that would suggest a broken or leaking line. The stock lines can get brittle with age and heat but like oem vac hoses, I think that’s usually only a problem if they’re disturbed. And they’re pretty deep to access.

Assuming a stock OMP system, as Sgtblue said, the ECU will put the car in limp mode if it detects any relevant problems on the electrical/control end of things. As for the mechanical aspect (does oil actually flow to the injectors?), all you can really do easily is visually inspect the lines to verify you can see oil actually flowing thru them (which is why I prefer the plastic OEM lines to any aftermarket braided SS lines), and check for oil leakage at each fitting and along the length of each line. You can also check your oil level frequently on the dipstick, but you typically you won't see much change there because the sump oil level lost via the OMP is probably a bit less than what the oil level will gain via fuel dilution over time. Which is why you want to do frequent oil changes with your rotary.