What is the test for an indigent defendant in a civil case?

shall be paid if the defendant is "permitted to sue or appeal in forma pauperis," and "if the trial judge . . . certifies" that (1) "the suit or appeal is not frivolous" and (2) "that the transcript is needed to decide the issue presented by the suit or appeal." 28 U.S.C. 753(f); see also Britt v. North Carolina, 404 U.S. 226, 227 (1971) (finding that an indigent prisoner must, as a matter of equal protection, be provided "with a transcript of prior proceedings when that transcript is needed for an effective defense or appeal").