What is the test for a person to use deadly force in self-defense?

"The principles of self-defense are founded in the doctrine of necessity. This foundation gives rise to two closely related rules. . . . First, only that force which is necessary to repel an attack may be used in self-defense; force which exceeds the necessity is not justified. [Citation.] Second, deadly force or force likely to cause great bodily injury may be used only to repel an attack which is in itself deadly or likely to cause great bodily injury; thus '[a] misdemeanor assault must be suffered without the privilege of retaliating with deadly force.' [Citations.]" (People v. Clark (1982) 130 Cal.App.3d 371, 380.)