Basically. Must crank certain amount of times. Must get certain values on all cylinders and then with all cylinders in comparison to eachother. Leakage test requires porting air to the cylinder with piston at tdc and measuring the leakdown rate. It is at this point you can tell if your exhaust valve, intake valve, head gasket, and piston conditions depending on where the air is pissing out. Normal condition is no air. Both valves are closed on tdc and piston rings should have minimal if no blow by.
