What is the test for admitting prior testimony of an unavailable witness?

Relying on authority regarding the admission of prior testimony of an unavailable witness and the constitutional right of confrontation, rather than the court's discretion under section 1050, defendant contends that this court must independently review the trial court's factual finding that the prosecution demonstrated due diligence. (See People v. Cromer (2001) 24 Cal.4th 889, 901.) Defendant also suggests that the trial court was required to hold the prosecution to the same strict standard of diligence to have a witness declared unavailable for purposes of admitting prior testimony. (See generally, People v. Herrera (2010) 49 Cal.4th 613, 621-622; Evid. Code, 240, subd. (a)(5), 1291.) We decline to expand the application of such principles to a motion to continue a probation hearing, as defendant has cited no authority for doing so and defendant's claim of error is not based upon the right of confrontation or the admission of prior testimony.