What is the test for a motion for a defendant to be treated as if he had not previously been convicted of serious and/or violent felonies?

prior serious and/or violent felony convictions, and the particulars of his background, character, and prospects, the defendant may be deemed outside the scheme's spirit, in whole or in part, and hence should be treated as though he had not previously been convicted of one or more serious and/or violent felonies." (People v. Williams (1998) 17 Cal.4th 148, 161.)

A decision granting or denying a so-called Romero motion is reviewed for abuse of discretion. (People v. Carmony (2004) 33 Cal.4th 367, 375.) We will not overturn a discretionary decision of a trial court absent a clear showing of abuse.