What is the test for admitting testimonial hearsay in a probation revocation hearing?

The parties agree, as do we, that "good cause" must be shown before testimonial hearsay may be admitted in a probation revocation hearing in lieu of live testimony. Good cause is met (1) if the declarant is unavailable; or (2) if the declarant cannot be brought to the hearing absent great difficulty or expense; or (3) if the declarant faces a risk of harm in testifying. (People v. Arreola (1994) 7 Cal.4th 1144, 1158-1160.) It is error to admit hearsay testimony to establish a violation of probation. (People v. Shepherd (2007) 151 Cal.App.4th 1193, 1202.)