What is the test for obtaining a certificate of appealability to appeal a district court's denial of a habeas petition?

Under AEDPA, a prisoner seeking to appeal a district court's denial of a habeas petition must obtain a certificate of appealability. 28 U.S.C. 2253(c)(1)(A). The district court may issue a certificate of appealability "only if the applicant has made a substantial showing of the denial of a constitutional right." 28 U.S.C. 2253(c)(2). To satisfy this standard, a 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).