What is the test for a plaintiff's claim that he was deprived of his constitutional right to testify?

We review "de novo a defendant's claim that he was deprived of his constitutional right to testify." United States v. Gillenwater, 717 F.3d 1070, 1076 (9th Cir. 2013).

"[A] defendant in a criminal case has the right to take the witness stand and to testify in his or her own defense." Id. at 1077 (internal quotation marks omitted). The same right applies in a competency hearing, a "critical stage" in the adversarial process. Id. at 1077 n.5. A defendant's right to testify is personal and therefore may be relinquished only by the defendant. Id. at 1079. Additionally, the "relinquishment of the right [to testify] must be knowing and intentional." Id. (internal quotation marks omitted). "[W]aiver of the right to testify may be inferred from the defendant's conduct and is presumed from the defendant's failure to testify or notify the court of his desire to do so." United States v. Joelson, 7 F.3d 174, 177 (9th Cir. 1993).