What is the test for the affirmative defense in a sexual assault case?

In considering the trial court's ruling, we first review the applicable law. " ' "[A] defendant has a constitutional right to have the jury determine every material issue presented by the evidence[.]" ' [Citation.] 'To protect this right and the broader interest of safeguarding the jury's function of ascertaining the truth, a trial court must instruct on lesser included offenses . . . whenever there is substantial evidence raising a question as to whether all of the elements of the charged offense are present.' [Citation.] Conversely, even on request, a trial judge has no duty to instruct on any lesser offense unless there is substantial evidence to support such instruction." (People v. Cunningham (2001) 25 Cal.4th 926, 1007-1008, italics omitted.) Likewise, a trial court need not give a requested instruction on an affirmative defense if there is insufficient evidence to support the instruction. (People v. Mentch (2008) 45 Cal.4th 274, 288.)