What is the legal test for aiding and abetting?

Instructions on aiding and abetting are appropriate when substantial evidence would support a conviction under that theory. (People v. Nguyen (1993) 21 Cal.App.4th 518, 528.) "To determine whether there is substantial evidence to support a conviction we must view the record in a light most favorable to conviction, resolving all conflicts in the evidence and drawing all reasonable inferences in support of conviction. We may conclude that there is no substantial evidence in support of conviction only if it can be said that on the evidence presented no reasonable fact finder could find the defendant to be guilty on the theory presented." (Id. at pp. 528-529.)