What is the test for determining whether a police officer's suspicion was constitutionally reasonable?

This determination is one of law for an appellate court, based upon the express and implicit findings of fact supporting the lower court's ruling. This court is thus required to make its own independent determination whether the officer's suspicion was constitutionally reasonable when the circumstances of this case are viewed most favorably in support of the challenged ruling. (People v. Leyba, supra, 29 Cal.3d at pp. 597-598, 174 Cal.Rptr. 867, 629 P.2d 961.)