What is the test for challenging jurisdiction under Rule 12 of the Civil Procedure 12(b)(1)?

Federal Rule of Civil Procedure 12(b)(1) provides a procedural mechanism for a defendant to challenge subject-matter jurisdiction. "A jurisdictional challenge under Rule 12(b)(1) may be made either on the face of the pleadings or by presenting extrinsic evidence. Where jurisdiction is intertwined with the merits, we must assume the truth of the allegations in a complaint unless controverted by undisputed facts in the record." Warren v. Fox Family Worldwide, Inc., 328 F.3d 1136, 1139 (9th Cir. 2003) (internal quotation marks, brackets, ellipsis and citations omitted).