What is the test for corroboration in a witness report?

generally is insufficient. [Citation.] Courts take a dim view of the significance of `pedestrian facts' such as a suspect's physical description, his residence and his vehicles. [Citation.] However, the corroboration is sufficient if police investigation has uncovered probative indications of criminal activity along the lines suggested by the informant. [Citation.] Even observations of seemingly innocent activity provide sufficient corroboration if the anonymous tip casts the activity in a suspicious light. [Citations.]" (People v. Johnson (1990) 220 Cal.App.3d 742, 749, 270 Cal. Rptr. 70.)