What is the test for admitting evidence that involves crimes other than those for which a defendant is being tried?

prejudice. . . . 'Evidence that involves crimes other than those for which a defendant is being tried is admitted only with caution, as there is the serious danger that the jury will conclude that defendant has a criminal disposition and thus probably committed the presently charged offense. [Citations.]' [Citation.]" (People v. Calderon, supra, 9 Cal.4th at p. 75.)

"[H]owever, bifurcation is not required in every instance. In some cases, a trial court properly may determine, prior to trial, that a unitary trial of the defendant's guilt or innocence of the charged offense and of the truth of a prior conviction allegation will not unduly prejudice the defendant. Perhaps the most common situation in which bifurcation of the determination of the truth of a prior conviction allegation is not required arises when, even if bifurcation were ordered, the jury still would learn of the existence of the prior conviction before returning a verdict of guilty." (People v. Calderon, supra, 9 Cal.4th at p. 78.)