What is the test for assisting and abetting in the commission of a crime?

"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 . . . are principals in any crime so committed." ( 31.) "[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 [with] (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.)

"Whether one has aided and abetted in the commission of a crime is a question of fact for the jury to determine from the totality of the circumstances proved. [Citation.] Factors which the jurors may consider in making such determination include presence at the crime, companionship and the conduct of the accused before and after the offense. [Citation.] (People v. Perryman (1967) 250 Cal.App.2d 813, 820.) "'[W]hile mere presence at the scene of an offense is not sufficient in itself to sustain a conviction, it is a circumstance which will tend to support a finding that an accused was a principal. [Citations.]' [Citation.]" (People v. Miranda (2011) 192 Cal.App.4th 398, 407.)