When it comes to testing a hydraulic system, there are three key tests that should be performed - pressure test, flow test and function test. The pressure test is important because it will tell you the condition of the seals in the system and help identify any areas where there may be leaks or weak points. For this test, you'll need to measure the average operating pressure at different times during normal operation so that any changes can be detected early on. The second type of testing is a flow test; this involves measuring how much fluid moves through each component in the system at various pressures over time. Finally, a functional test should also be carried out which assesses whether all components are working correctly together and if certain functions perform as expected under certain conditions. By performing these three tests regularly on your hydraulic system, you can ensure that it's running efficiently and effectively for many years to come without unexpected breakdowns or costly repairs!