What is the test for a motion to suppress a search and seizure where methamphetamine was found during a search?

Defendant filed a motion to suppress (Pen.Code, 1538.5 ), alleging that he was detained and searched without probable cause, reasonable suspicion, or valid consent. Defendant asserted that the prosecution was obligated to justify the warrantless search and seizure. (See People v. Williams (1999) 20 Cal.4th 119, 130, 83 Cal.Rptr.2d 275, 973 P.2d 52.) The prosecution filed a written response, arguing that there was reasonable suspicion to justify defendant's initial detention as well as the subsequent pat search, and that the methamphetamine was found pursuant to a lawful search incident to arrest. After a hearing, the trial court denied the motion to suppress.