def METHOD_NAME(self):
    """
    Test whether overriden validate method validates that the submitted path
    has not been already registered.
    """
    path = 'SERVICES/MyService/123456-crazy/brain_crazy_study/brain_crazy_mri/file1.dcm'
    data = {'service_name': 'MyService', 'path': path}
    servicefiles_serializer = ServiceFileSerializer()
    service = Service(identifier='MyService')
    service.save()
    service_file = ServiceFile(service=service)
    service_file.fname.name = path
    service_file.save()
    with self.assertRaises(serializers.ValidationError):
        servicefiles_serializer.validate(data)