What is the test for assisting and abetting a murder?

The record also contains ample evidence that defendant aided and abetted the killing. "[A] person aids and abets the commission of a crime when he or she, acting with (1) knowledge of the unlawful purpose of the perpetrator; and (2) the intent or purpose of committing, encouraging, or facilitating the commission of the offense, (3) by act or advice aids, promotes, encourages, or instigates, the commission of the crime." (People v. Beeman (1984) 35 Cal.3d 547, 561, 199 Cal.Rptr. 60, 674 P.2d 1318 ; accord, People v. Prettyman (1996) 14 Cal.4th 248, 259, 58 Cal.Rptr.2d 827, 926 P.2d 1013.)