from django.db import models

from django.test import SimpleTestCase

from django.test.utils import isolate_apps

@isolate_apps("invalid_models_tests")

class CustomFieldTest(SimpleTestCase):

    def test_none_column(self):

        class NoColumnField(models.AutoField):

            def db_type(self, connection):

                # None indicates not to create a column in the database.

                return None

        class Model(models.Model):

            field = NoColumnField(primary_key=True, db_column="other_field")

            other_field = models.IntegerField()

        field = Model._meta.get_field("field")

        self.assertEqual(field.check(), [])