What is the test for a warrantless search?

^12. "[T]he exigent circumstances doctrine constitutes an exception to the warrant requirement when an emergency situation requires swift action to prevent imminent danger to life." (People v. Rogers, supra, 46 Cal.4th at p. 1156.) " ' " '[T]here is no ready litmus test for determining whether such circumstances exist, and in each case the claim of an extraordinary situation must be measured by the facts known to the officers.' " ' [Citation.]" (Id. at p. 1157; see also People v. Green (1971) 15 Cal.App.3d 766 [exigent circumstances justified warrantless search of defendant's car, based on reports that defendant had placed a bag containing a gun under the hood of his car].)