What is the test for an evidentiary hearing where a petitioner alleges severe mental impairment during the filing period?

A petitioner alleging a severe mental impairment during the filing period is not entitled to an evidentiary hearing unless he or she makes "a good faith allegation that would, if true, entitle him to equitable tolling." Laws v. Lamarque, 351 F.3d 919, 921 (9th Cir. 2003) (remanding for consideration of whether the petitioner's delayed filing was "attributable to psychiatric medication which deprived petitioner of any kind of consciousness" where the petitioner had demonstrated "evidence of serious mental illness" by attaching prison psychiatric and medical records).