That'* a leak down test, a little different. compression test looks for peak compression, a leak down test looks for loss of pressure over time. Both are good tests.

Iits called a wet and dry test test them all dry first.... Then try them after you squirted oil into the cylinder if the compression increases with the oil in there you have worn rings. If it stays the same its most likely worn valves. assuming your having compression problems in some cases.