What is the test for a motion to suppress?

trial court's ruling is not supported by substantial evidence. "'"An appellate court's review of a trial court's ruling on a motion to suppress is governed by well-settled principles. [Citations.] [] In ruling on such a motion, the trial court (1) finds the historical facts, (2) selects the applicable rule of law, and (3) applies the latter to the former to determine whether the rule of law as applied to the established facts is or is not violated. [Citations.] 'The [trial] court's resolution of each of these inquiries is, of course, subject to appellate review.' [Citations.] [] The court's resolution of the first inquiry, which involves questions of fact, is reviewed under the deferential substantial-evidence standard. [Citations.] Its decision on the second, which is a pure question of law, is scrutinized under the standard of independent review. [Citations.] Finally, its ruling on the third, which is a mixed fact-law question that is however predominantly one of law, . . . is also subject to independent review."' [Citation.]" (People v. Ayala (2000) 23 Cal.4th 225, 255.)