What is the test for advising a witness not to testify?

[Citation.]" (People v. Warren (1984) 161 Cal.App.3d 961, 972, fn. omitted.) The court may advise the witness or appoint counsel to advise the witness. (Schroeder, supra, at p. 788.) If the court chooses to advise the witness, it must do so in such a way as to fully advise the witness of the risks of testifying and the right not to testify, but not to coerce the witness not to testify. (Id. at p. 789.) The coerciveness of an advisement is evaluated in light of all of the circumstances. (Id. at p. 793.)