What is the test for determining whether a defendant can be convicted of a lesser included crime under section 1097 of the California Public Prosecutions Act?

Section 1097 provides: "When it appears that the defendant has committed a public offense, or attempted to commit a public offense, and there is reasonable ground of doubt in which of two or more degrees of the crime or attempted crime he is guilty, he can be convicted of the lowest of such degrees only." In People v. Dewberry (1959) 51 Cal.2d 548, at page 555 (Dewberry), the court held: "[W]hen the evidence is sufficient to support a finding of guilt of both the offense charged and a lesser included offense, the jury must be instructed that if they entertain a reasonable doubt as to which offense has been committed, they must find the defendant guilty only of the lesser offense."