What is the test for voluntary intoxication in a sexual assault case?

voluntary intoxication shall not be admitted to negate the capacity to form any mental states ... " such as "purpose, intent, [or] knowledge" except such evidence "is admissible ... on the issue of whether or not the defendant actually formed a required specific intent."]; People v. Stanley (1992) 6 Cal.App.4th 700, 706, 7 Cal.Rptr.2d 881 [voluntary intoxication cannot be used to support a defense to rape based upon a reasonable mistake of fact].)