Completed tests go to Testing → History and stay there for good. A test never comes back: the next test of that control is a new one.
The most recently completed are at the top; more load as you scroll.
Search covers all of history, not just what's loaded.
Click a test to see its summary, or open it to see every answer, the evidence and the sign-off.
Each unit's own tests are also in the Tests tab of its history, on the unit screen.