What is the test for a search without a warrant or probable cause?

"The scope of intrusion permitted without a warrant or probable cause 'will vary to some extent with the particular facts and circumstances of each case,' and there is no 'litmus-paper test' for distinguishing an investigatory stop from a full arrest. [Citations.] Consequently, we must consider the totality of the circumstances [citation] to determine if the means used by the police, including detention at gunpoint, were justified by the need of a 'reasonably prudent' officer [citation] to protect himself and others involved in the search." (People v. Glaser, supra, 11 Cal.4th at p. 366, 45 Cal.Rptr.2d 425, 902 P.2d 729.)