'The fields option allows to define a subset of fields to be present in
the \'properties\' of the generated output.'

def test_fields_option(self):

    PennsylvaniaCity.objects.create(name='Mansfield', county='Tioga', point='POINT(-77.071445    41.823881)')
    geojson = serializers.serialize('geojson', PennsylvaniaCity.objects.all(), fields=('county', 'point'))
    geodata = json.loads(geojson)
    self.assertIn('county', geodata['features'][0]['properties'])
    self.assertNotIn('founded', geodata['features'][0]['properties'])
    self.assertNotIn('pk', geodata['features'][0]['properties'])
