What is the test for premeditation and deliberation in a murder case?

Such a scenario indicates premeditation and deliberation, not conduct based "upon a 'sudden and unconsidered impulse[].' " (People v. Wickersham, supra, 32 Cal.3d at p. 330.) "[I]f sufficient time has elapsed between the provocation and the fatal blow for passion to subside and reason to return, the killing is not voluntary manslaughter." (Id. at p. 327.) Evidence of preplanning shows the defendant's passion had subjectively cooled before the murder. (People v. Golsh (1923) 63 Cal.App. 609, 617.)