An oil pressure test should be checks of the oil pressure at idle, at 1,000 rpm, at 2,000 rpm, and at 3,000 rpm. YOU could do these checks with a $15 oil pressure test gauge.
If the oil pressure is OK at rpms above idle, it shows that the oil pump is up to the task; though, the engine may be rather worn. If it is OK at the higher rpms, you can nurse some more time out of the engine.