What is the test for a motion for a new trial based on newly discovered evidence?

"'"The determination of a motion for a new trial rests so completely within the court's discretion that its action will not be disturbed unless a manifest and unmistakable abuse of discretion clearly appears."' [Citations.] '"[I]n determining whether there has been a proper exercise of discretion on such motion, each case must be judged from its own factual background."' [Citations.] [] In ruling on a motion for new trial based on newly discovered evidence, the trial court considers the following factors: '"1. That the evidence, and not merely its materiality, be newly discovered; 2. That the evidence be not cumulative merely; 3. That it be such as to render a different result probable on a retrial of the cause; 4. That the party could not with reasonable diligence have discovered and produced it at the trial; and 5. That these facts be shown by the best evidence of which the case admits."' [Citations.]" (People v. Delgado (1993) 5 Cal.4th 312, 328.) "In addition, 'the trial court may consider the credibility as well as materiality of the evidence in its determination [of] whether introduction of the evidence in a new trial would render a different result reasonably probable.'" (Id. at p. 329.)