What is the test for a motion for nonsuit in a medical malpractice case where plaintiff failed to produce expert testimony?

We conclude that since plaintiff could not prove his case for legal malpractice without the opinion testimony of an expert witness, and because plaintiff was barred from introducing such evidence pursuant to Code of Civil Procedure section 2034.300, the trial court correctly granted the motion for nonsuit. (Lipscomb v. Krause (1978) 87 Cal.App.3d 970, 975-976 [where plaintiff failed to produce expert testimony on standard of care, grant of nonsuit affirmed].)