What is the test for a "aider and abettor" to be convicted of a specific intent crime?

1118.) When the offense is a specific intent offense, '"the accomplice must 'share the specific intent of the perpetrator'; this occurs when the accomplice 'knows the full extent of the perpetrator's criminal purpose and gives aid or encouragement with the intent or purpose of facilitating the perpetrator's commission of the crime.'"' (Ibid.)In the case of murder, the aider and abettor 'must know and share the murderous intent of the actual perpetrator.' (Ibid.)[] Though McCoy concluded that an aider and abettor could be guilty of a greater offense than the direct perpetrator, its reasoning leads inexorably to the further conclusion that an aider and abettor's guilt may also be less than the perpetrator's, if the aider and abettor has a less culpable mental state. (See People v. Woods (1992) 8 Cal.App.4th 1570, 1577 [11 Cal.Rptr.2d 231].) Consequently, CALCRIM No. 400's direction that '[a] person is equally guilty of the crime [of which the perpetrator is guilty] whether he or she committed it personally or aided and abetted the perpetrator who committed it' (CALCRIM No. 400, italics added), while generally correct in all but the most exceptional circumstances, is misleading here and should have been modified."