What is the test for a police officer to conduct a search and seizure under the Fourth Amendment?

a police officer, without more, convert the encounter into a seizure requiring some level of objective justification. [Citation.] The person approached, however, need not answer any question put to him; indeed, he may decline to listen to the questions at all and may go on his way. [Citations.] He may not be detained even momentarily without reasonable, objective grounds for doing so; and his refusal to listen or answer does not, without more, furnish those grounds. [Citation.] If there is no detentionno seizure within the meaning of the Fourth Amendmentthen no constitutional rights have been infringed." (Florida v. Royer (1983) 460 U.S. 491, 497-498, 103 S.Ct. 1319, 75 L.Ed.2d 229, italics added.)