What is the test for credibility of a witness in a civil case?

evidence in the light most favorable to the People and must presume in support of the judgment the existence of every fact the trier could reasonably deduce from the evidence. [Citation.] [] Although we must ensure the evidence is reasonable, credible, and of solid value, nonetheless it is the exclusive province of the trial judge or jury to determine the credibility of a witness and the truth or falsity of the facts on which that determination depends. [Citation.] Thus, if the verdict is supported by substantial evidence, we must accord due deference to the trier of fact and not substitute our evaluation of a witness's credibility for that of the fact finder. [Citations.]' [Citation.]" (People v. Ochoa (1993) 6 Cal.4th 1199, 1206; see People v. Smith (2005) 37 Cal.4th 733, 738-739.)