What is the test for credibility of a witness at a sexual assault hearing?

^13. J.Q. complains "her demeanor when explaining her side of the story are hardly the issue here[.]" She is wrong. "[T]he court . . . may consider in determining the credibility of a witness any matter that has any tendency in reason to prove or disprove the truthfulness of [her] testimony at the hearing, including but not limited to any of the following: [] [Her] demeanor while testifying and the manner in which [she] testifies." (Evid. Code, 780, subd. (a); People v. Jackson (1989) 49 Cal.3d 1170, 1205-1206.)