What is the test for denying a defendant's right to cross-examine a witness at the preliminary hearing?

It is obvious that a denial of the right to cross-examine a witness at the preliminary hearing takes on a different aspect if the testimony of that witness given at the preliminary hearing is used in his absence at the trial. The actual denial of the right of cross-examination in such situation is a denial of the right of confrontation guaranteed by the Sixth Amendment of the Federal Constitution (Pointer v. State of Texas, 380 U.S. 400, 85 S.Ct. 1065, 13 L.Ed.2d 923).