What is the constitutional right of a defendant in a sexual assault case to cross-examine the witness?

"The constitutional right implicated here is the right of an accused in a criminal prosecution 'to be confronted with the witnesses against him.' [Citations.] This confrontation right seeks 'to ensure that the defendant is able to conduct a "personal examination and cross-examination of the witness, in which [the defendant] has an opportunity, not only of testing the recollection and sifting the conscience of the witness, but of compelling him to stand face to face with the jury in order that they may look at him, and judge by his demeanor upon the stand and the manner in which he gives his testimony whether he is worthy of belief."' [Citation.] To deny or significantly diminish this right deprives a defendant of the essential means of testing the credibility of the prosecution's witnesses, thus calling 'into question the ultimate "'integrity of the fact-finding process.'"' [Citation.]" (People v. Cromer (2001) 24 Cal.4th 889, 896-897 (Cromer).)