What is the test for determining a spouse's ability to earn as distinguished from actual income?

By way of analogy, the law provides an award of spousal or child support will be based on the supporting spouse's ability to earn as distinguished from actual income, where the supporting spouse "is, in effect, acting in bad faith by either refusing work or engaging in other conduct designed to reduce ... income." (In re Marriage of Rome, supra, 109 Cal.App.3d at p. 965, 167 Cal.Rptr. 351; accord Philbin v. Philbin (1971) 19 Cal.App.3d 115, 121, 96 Cal.Rptr. 408.)