What is the test for assisting and abetting a lewd act on a child?

Under section 288, any person who willfully and lewdly commits, by use of force, violence, duress, menace or fear of immediate and unlawful bodily injury, any lewd or lascivious act on a child who is under the age of 14 years, with the intent of arousing, appealing to, or gratifying the lust, passions, or sexual desires of that person or the child, is guilty of a felony. ( 288, subd. (b)(1).) A person may aid and abet a lewd act when he or she assists the direct perpetrator by aid or encouragement, with knowledge of the perpetrator's criminal intent and with the intent to help him carry out the offense. (People v. Beeman (1984) 35 Cal.3d 547, 561.) Relevant factors to consider whether one is an aider and abettor include presence at the scene of the crime, companionship, and conduct before and after the offense. (Ibid.; see also People v. Campbell (1994) 25 Cal.App.4th 402, 409.)