What is the test for corroboration of testimony of two police officers in a criminal case?

In his brief in propria persona, filed before the appointment of counsel, defendant contends that the testimony of the officers cannot support a conviction on the ground that it is uncorroborated, citing People v. Reingold, 87 Cal.App.2d 382, 392, 197 P.2d 175. That case was concerned with corroboration of testimony by an accomplice as required by section 1111 of the Penal Code. The officers were not accomplices of the defendant and their testimony need not be corroborated.