What is the test for challenging a sentence in a criminal case?

Appellant did not challenge his plea agreement or his agreed-upon sentence in the trial court at any time. If he is now dissatisfied with the sentence to which he agreed and intends, by his supplemental brief, to challenge that sentence now, he cannot proceed in this court without first obtaining a certificate of probable cause from the trial court. (People v. Buttram (2003) 30 Cal.4th 773, 784-785 [a challenge to a sentence actually challenges the validity of the plea if the sentence is part of a plea bargain, requiring a certificate of probable cause to proceed on appeal].)

The judgment is affirmed.