What is the test for cross-examination of a defendant who voluntarily testifies on his own behalf?

Where, as here, "a defendant voluntarily testifies, the district attorney may fully amplify his testimony by inquiring into the facts and circumstances surrounding his assertions, or by introducing evidence through cross-examination which explains or refutes his statements or the inferences which may necessarily be drawn from them." (People v. Cooper (1991) 53 Cal.3d 771, 822.) A defendant who elects to testify on his own behalf is not entitled to a false aura of credibility. (People v. Carpenter (1999) 21 Cal.4th 1016, 1056.) "Although a defendant cannot be compelled to be a witness against himself, if he takes the stand and makes a general denial of the crime with which he is charged, the permissible scope of cross-examination is 'very wide.' [Citation.]" (People v. Cooper, supra, at p. 822.) As a result, a testifying defendant may be properly impeached with a statement made by him that is inconsistent with any part of his testimony. (Evid. Code, 780, 1101, subd. (c).)