What is the test for a conspiracy to commit a crime?

"A conviction of conspiracy requires proof that the defendant and another person had the specific intent to agree or conspire to commit an offense, as well as the specific intent to commit the elements of that offense, together with proof of the commission of an overt act by one or more of the parties to such agreement in furtherance of the conspiracy." ( People v. Morante (1999) 20 Cal.4th 403, 416, 84 Cal.Rptr.2d 665, 975 P.2d 1071.) Also, conspiracy provides a basis for vicarious criminal liability. Thus, members of a conspiracy are liable not only for the target crime, but also for any crimes that are the natural and probable consequence of the target crime. ( People v. Zacarias (2007) 157 Cal.App.4th 652, 657, 660, 69 Cal.Rptr.3d 81.)