What is the test for providing expert testimony in a personal injury case?

The purpose of the foregoing provisions is to give fair notice of what an expert will say at trial and to enable the opposing party to fully explore the relevant subject area at deposition. (Bonds v. Roy (1999) 20 Cal.4th 140, 146-147 (Bonds).) "It makes little practical difference whether the party proffering the expert testimony failed to submit an expert witness declaration or submitted an inaccurate one." (Id. at p. 147.) In either case, the opposing party is denied fair notice of the expected testimony.