TransactionTestCase.reset_sequences doesn't reset sequences of auto created ManyToMany models

[Oliver Sauder]

Consider following example:

class Person(models.Model):
    first_name = models.CharField(max_length=20)
    last_name = models.CharField(max_length=20)

    friends = models.ManyToManyField('self')

class AutoIncrementResetTest(TransactionTestCase):
    reset_sequences = True

    def test_autoincrement_reset1(self):
        p = Person.objects.create(first_name='Jack', last_name='Smith')
        self.assertEqual(p.pk, 1)

        p.friends.add(Person.objects.create(first_name='Jacky', last_name='Smith'))
        self.assertEqual(p.friends.through.objects.first().pk, 1)

    def test_autoincrement_reset2(self):
        p = Person.objects.create(first_name='Jack', last_name='Smith')
        self.assertEqual(p.pk, 1)

        p.friends.add(Person.objects.create(first_name='Jacky', last_name='Smith'))
        self.assertEqual(p.friends.through.objects.first().pk, 1)

Test test_autoincrement_reset2 will fail with a much higher primary key, indicating that sequence has not been properly reset. Tested this on a Postgres database but I assume this error exist on other databases as well.

[Oliver Sauder]

​PR

[Tim Graham <timograham@…>]

In a07a49ee:

Fixed #29559 -- Fixed TransactionTestCase.reset_sequences for auto-created m2m through models.