What is the test for "common design" in a criminal case?

and the charged offense) is required in order to prove intent. [Citation.] . . . In order to be admissible to prove intent, the uncharged misconduct must be sufficiently similar to support the inference that the defendant " 'probably harbor[ed] the same intent in each instance.' " ' [Citation.] Greater similarity is required to prove the existence of a common design or plan. In such a case, evidence of uncharged misconduct must demonstrate ' "not merely a similarity in the results, but such a concurrence of common features that the various acts are naturally to be explained as caused by a general plan of which they are the individual manifestations." [Citation.]' [Citation.] To show a common design, 'evidence that the defendant has committed uncharged criminal acts that are similar to the charged offense may be relevant if these acts demonstrate circumstantially that the defendant committed the charged offense pursuant to the same design or plan he or she used in committing the uncharged acts.' " (People v. Leon, supra, 61 Cal.4th at p. 598.)