What is the test for reducing a plaintiff's attorney fees for work on unsuccessful claims?

cause of action, the trial court cited Mann v. Quality Old Time Service, Inc. (2006) 139 Cal.App.4th 328, 342 for the proposition that "attorney fees need not be reduced for work on unsuccessful claims if the claims 'are so intertwined that it would be impracticable, if not impossible, to separate the attorney's time into compensable and noncompensable units.' [Citations.]" The trial court also noted that Teresa suffered no damages from South Shores's improper notice of eviction.