'When a model has several geometry fields, the \'geometry_field\' option
can be used to specify the field to use as the \'geometry\' key.'

def test_geometry_field_option(self):

    MultiFields.objects.create(city=City.objects.first(), name='Name', point=Point(5, 23), poly=Polygon(LinearRing((0, 0), (0, 5), (5, 5), (5, 0), (0, 0))))
    geojson = serializers.serialize('geojson', MultiFields.objects.all())
    geodata = json.loads(geojson)
    self.assertEqual(geodata['features'][0]['geometry']['type'], 'Point')
    geojson = serializers.serialize('geojson', MultiFields.objects.all(), geometry_field='poly')
    geodata = json.loads(geojson)
    self.assertEqual(geodata['features'][0]['geometry']['type'], 'Polygon')
    geojson = serializers.serialize('geojson', MultiFields.objects.all(), geometry_field='poly', fields=('city',))
    geodata = json.loads(geojson)
    self.assertEqual(geodata['features'][0]['geometry']['type'], 'Polygon')
