What is the test for obtaining attorney fees under California Code of Civil Procedure section 1021.5?

To obtain fees under Code of Civil Procedure section 1021.5, the moving party must establish all of the following: (1) he or she is a "successful party," (2) the action has resulted in the enforcement of an important right affecting the public interest, (3) the action has conferred a significant benefit on the public or a large class of persons, and (4) an attorney fees award is appropriate in light of the necessity and financial burden of private enforcement. ( Sagaser v. McCarthy (1986) 176 Cal.App.3d 288, 313, 221 Cal.Rptr. 746.)