testing - Grails: How to mock a domain field validator? -

is there way mock domain field validator?
currently, code in domain class looking this:

isprimary(validator: { boolean value, person obj ->      ....... } 

and need mock function.

i tried use like:

person.metaclass.static.isprimary.validator = { boolean value, person obj ->      ....... } 

and didn't work, suggestions how solve issue ?

here example:

class person {     boolean isprimary      static constraints = {         isprimary validator: isprimaryvalidator          //or qualified validator         //isprimary validator: person.isprimaryvalidator     }      static isprimaryvalidator = { boolean value, person obj ->         //some validation     } }  //in test person.metaclass.'static'.isprimaryvalidator = { boolean value, person obj ->      //do else }