What is the test for determining whether a defendant intended his words to be taken as a threat?

Moreover, "the determination whether a defendant intended his words to be taken as a threat, and whether the words were sufficiently unequivocal, unconditional, immediate and specific [that] they conveyed to the victim an immediacy of purpose and immediate prospect of execution of the threat can be based on all the surrounding circumstances and not just on the words alone. The parties' history can also be considered as one of the relevant circumstances." (People v. Mendoza (1997) 59 Cal.App.4th 1333, 1340, bracketed material added.)