import unittest

from django.db import connection

from django.test import TestCase

from ..models import Person

@unittest.skipUnless(connection.vendor == "postgresql", "Test only for PostgreSQL")

class DatabaseSequenceTests(TestCase):

    def test_get_sequences(self):

        with connection.cursor() as cursor:

            seqs = connection.introspection.get_sequences(cursor, Person._meta.db_table)

            self.assertEqual(

                seqs,

                [

                    {

                        "table": Person._meta.db_table,

                        "column": "id",

                        "name": "backends_person_id_seq",

                    }

                ],

            )

            cursor.execute("ALTER SEQUENCE backends_person_id_seq RENAME TO pers_seq")

            seqs = connection.introspection.get_sequences(cursor, Person._meta.db_table)

            self.assertEqual(

                seqs,

                [{"table": Person._meta.db_table, "column": "id", "name": "pers_seq"}],

            )

    def test_get_sequences_old_serial(self):

        with connection.cursor() as cursor:

            cursor.execute("CREATE TABLE testing (serial_field SERIAL);")

            seqs = connection.introspection.get_sequences(cursor, "testing")

            self.assertEqual(

                seqs,

                [

                    {

                        "table": "testing",

                        "column": "serial_field",

                        "name": "testing_serial_field_seq",

                    }

                ],

            )