What is the test for a motion to grant a continuance under the Speedy Trial Act?

The Speedy Trial Act provides, inter alia, that the district court may grant a continuance on the request of either side or on its own motion, and that the resulting delay may be excluded from the 70-day computation if the court (1) finds "that the ends of justice served by the granting of such continuance outweigh the best interests of the public and the defendant in a speedy trial," and (2) sets forth its reasons for that finding on the record. Id. Sec. 3161(h)(8)(A); see also United States v. Tunnessen, 763 F.2d 74, 76-78 (2d Cir.1985) (finding must be made before excludable period begins). Among the factors the court may consider in making such a finding is that