Hi my name is Tan I will assist you.
If the cooling system is working properly then engine will not over heat and the water indicator will flow a strong stream of water. This in itself is the test. The engine has a temp sensor on each cylinder head that monitors the engine temp. If the engine over heats the engine over heat alarm will sound. Then the tell tale is the visual indicator that the engine is pumping water. These are all you need to determine that the cooling system is functioning properly. If you want more info on the cooling system as to temp you can use a Infra red temp gun to check the temp while running through out the rpm range.
If you follow the maintenance recommendations you will have a trouble free motor. The engine should be serviced every 100 hours of use or once a season or which ever comes first.