What is the legal test for a motion to suppress evidence in a sexual assault case?

We appointed counsel to represent appellant on appeal. After examining the record, counsel filed an opening brief pursuant to People v. Wende (1979) 25 Cal.3d 436, raising no issues, but requesting that this court independently review the entire record to determine if there are any issues, which if resolved in appellant's favor, would require reversal or modification of the judgment. On August 6, 2013, we gave notice to appellant that his appointed counsel had not found any arguable issues, and that he had 30 days within which to submit by brief or letter any grounds of appeal, contentions, or arguments he wanted this court to consider. On September 3, 2013, appellant submitted an eight-page brief contending that the trial court erred in denying his motion to suppress evidence.