What is the test for a discretionary motion for relief under section 473 of the California Code of Civil Procedure?

"'[T]o warrant relief under [Code of Civil Procedure] section 473[,] a litigant's neglect must have been such as might have been the act of a reasonably prudent person under the same circumstances. The inadvertence contemplated by the statute does not mean mere inadvertence in the abstract. If it is wholly inexcusable it does not justify relief." (Hearn v. Howard (2009) 177 Cal.App.4th 1193, 1206.) "Generally speaking, the trial court's ruling on a discretionary motion for relief is reviewed for an abuse of discretion. [Citation.]" (Henderson, supra, 187 Cal.App.4th at p. 230.)