'If you specify an existing primary key, but different other fields,
then you will get an error and data will not be updated.'

def test_manual_primary_key_test(self):

    ManualPrimaryKeyTest.objects.create(id=1, data='Original')
    with self.assertRaises(IntegrityError):
        ManualPrimaryKeyTest.objects.update_or_create(id=1, data='Different')
    self.assertEqual(ManualPrimaryKeyTest.objects.get(id=1).data, 'Original')
