What is the legal test for instructing a jury on an aiding and abetting liability theory?

"`The test for determining whether instructions on a particular theory of guilt are appropriate is whether there is substantial evidence which would support conviction on that theory. [Citation.] 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 guilty on the theory presented. [Citation.]' [Citations.]" (People v. Campbell (1994) 25 Cal.App.4th 402, 408.)

Under Penal Code section 31, "All persons concerned in the commission of a crime, . . . whether they directly commit the act constituting the offense, or aid and abet in its commission, or, not being present, have advised and encouraged its commission, . . . are principals in any crime so committed," and therefore one "who aids and abets a crime is guilty of that crime even if someone else committed some or all of the criminal acts. [Citation.]" (People v. McCoy (2001) 25 Cal.4th 1111, 1117.) But "for a defendant to be found guilty under an aiding and abetting theory, someone other than the defendant must be proven to have attempted or committed a crime; i.e., absent proof of a predicate offense, conviction on an aiding and abetting theory cannot be sustained." (People v. Perez (2005) 35 Cal.4th 1219, 1225.) "Without proof of a criminal act by [a perpetrator] to which [the defendant] contributed, the prosecution could not convict [the defendant] as an aider and abettor. [Citations.]" (Id. at p. 1227.)

In People v. Singleton (1987) 196 Cal.App.3d 488, after stopping a car in which the defendant was riding as a passenger, the police found numerous bindles of cocaine in one of her boots. Charged with possessing cocaine for sale, the defendant claimed the driver gave her the bindles and asked her to hide them for him. The trial court instructed the jury on an aiding and abetting liability theory because the prosecutor contended she could be found guilty if she assisted someone, other than the driver, sell the cocaine.