What is the test for reviewing an order granting or denying attorney fees under section 1021.5?

"Generally, an order granting or denying attorney fees under section 1021.5 is reviewed for abuse of discretion." (Bui v. Nguyen (2014) 230 Cal.App.4th 1357, 1367.) "[T]he award will be upheld unless ' "there is no substantial evidence to support the trial court's findings or when there has been a miscarriage of justice. If the trial court has made no findings, the reviewing court will infer all findings necessary to support the judgment and then examine the record to see if the findings are based on substantial evidence." ' " (Id. at p. 1368.)