What is the test for corroborating evidence in a sexual assault case?

"To corroborate the testimony of an accomplice, the prosecution must present independent evidence which, without aid or direction from the testimony of the accomplice, tends reasonably to connect the defendant with the commission of the crime charged. [Citation.] Corroborating evidence is insufficient if it does no more than cast a 'grave suspicion' upon the accused, or merely connects him with the crime's perpetrators. [Citation.] While the corroborating evidence need not support every fact to which the accomplice has testified, it must tend to implicate the defendant and therefore must relate to some act or fact which is an element of the crime. [Citations.]" (People v. Mardian (1975) 47 Cal.App.3d 16, 42, 121 Cal.Rptr. 269; italics added.)