When we had our old Dometic fridge replaced with a new one earlier this year, one of the checks the installer at the RV repair place did was a 24-hour leak test on the fridge's propane system.
As I understood it, the system had a pressure gauge installed at the propane inlet to the fridge. The system was pressurized from the propane tank and then the tank valve was closed. After 24 hours there was no change to the pressure in the fridge line.
Frank and Eileen
No longer RVers or FR owners