'Ensuring exceptions are raised for operators & functions invalid on geography fields.'

@skipUnless(postgis, 'This    is    a    PostGIS-specific    test')
def test04_invalid_operators_functions(self):

    z = Zipcode.objects.get(code='77002')
    with self.assertRaises(ValueError):
        City.objects.filter(point__within=z.poly).count()
    with self.assertRaises(ValueError):
        City.objects.filter(point__contained=z.poly).count()
    htown = City.objects.get(name='Houston')
    with self.assertRaises(ValueError):
        City.objects.get(point__exact=htown.point)
