What is the legal test for appealing a District Court's denial of a Petitioner's application to obtain a Certificate of Appealability?

To appeal a district court's denial of a 2255 petition, a petitioner must obtain a certificate of appealability. 28 U.S.C. 2253(c)(1)(A). A district court may issue a certificate of appealability only if the applicant has made a substantial showing of the denial of a constitutional right. Id. 2253(c)(2). To satisfy this standard, the petitioner must show that reasonable jurists would find the district court's assessment of the constitutional claims debatable or wrong. Slack v. McDaniel, 529 U.S. 473, 484 (2000).