What is the test for determining whether a defendant is guilty of a lesser included crime of theft?

"The trial court must instruct on general legal principles closely related to the case. This duty extends to necessarily included offenses when the evidence raises a question as to whether all the elements of the charged offense are present. [Citation.] It is settled that the crime of theft, whether divided by degree into grand theft or petty theft, is a lesser included offense of robbery. [Citation.] Robbery includes the added element of force or fear. [Citation.]" (People v. DePriest (2007) 42 Cal.4th 1, 50 (DePriest).)

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