What is the test for dismissing a claim as moot?

"As a general rule, ' " 'the duty of this court, as of every other judicial tribunal, is to decide actual controversies by a judgment which can be carried into effect, and not to give opinions upon moot questions or abstract propositions, or to declare principles or rules of law which cannot affect the matter in issue in the case before it.' " ' [Citation.] Thus, an ' "action that originally was based on a justiciable controversy cannot be maintained on appeal if all the questions have become moot by subsequent acts or events." ' [Citations.] Put another way, ' "[a]n appeal should be dismissed as moot when the occurrence of events renders it impossible for the appellate court to grant appellant any effective relief." ' " (People v. Pipkin (2018) 27 Cal.App.5th 1146, 1149-1150.)