What is the test to establish a violation of the constitutional right to effective assistance of counsel?

"To establish a violation of the constitutional right to effective assistance of counsel, a defendant must show both that his counsel's performance was deficient when measured against the standard of a reasonably competent attorney and that this deficient performance caused prejudice in the sense that it 'so undermined the proper functioning of the adversarial process that the trial cannot be relied on as having produced a just result.' [Citations.] If a defendant has failed to show that the challenged actions of counsel were prejudicial, a reviewing court may reject the claim on that ground without determining whether counsel's performance was deficient. [Citation.]" (People v. Kipp (2001) 26 Cal.4th 1100, 1122-1123.)