Not able to execute tests while using JSON converters

[Buddha Shrestha]

Hi,

I'm doing a small test on grails 3.2 using JSON converters(deep)

These are my domain.

class Parent{
   String name
    static hasMany = [childs:Child] 
    static constraints = {
   }
}


class Child{
   String name
   static belongsTo = [parent:Parent]
   static constraints={}
}

And I used 'deep' converter to get all the information. My controller looks like this:

def getParents() {
        def parentList = Parent.findAllById(params?.id)
        JSON.use('deep')
           render parentList as JSON

}

These controllers provide me correct response. But when I try to implement this into a unit test which looks like this: 

    void 'test check status'() {
        when:
        request.method = 'GET'
        request.contentType = 'application/json'
        new Parent(name: 'XYZ', child: new Child(name: 'Demo')).save()
        params.id = '1'
        request.contentType = 'application/json'
        controller.getParents()

        then:
        response.status == HttpStatus.SC_OK
    }

But. when I try to test this, I get an error like :

org.grails.web.converters.exceptions.ConverterException: Error converting Bean with class **********

I'm confused what should I do. Please suggest.

Thanks,