What is the test for determining the earning capacity of a parent in lieu of the child's income?

"The court may, in its discretion, consider the earning capacity of a parent in lieu of the parent's income, consistent with the best interests of the children." (Fam. Code, 4058, subd. (b).) "'Earning capacity is composed of (1) the ability to work, including such factors as age, occupation, skills, education, health, background, work experience and qualifications; (2) the willingness to work exemplified through good faith efforts, due diligence and meaningful attempts to secure employment; and (3) an opportunity to work which means an employer who is willing to hire.'" (Mendoza v. Ramos (2010) 182 Cal.App.4th 680, 685.)