from unittest import mock, skipUnless

from django.db import connection

from django.db.backends.mysql.features import DatabaseFeatures

from django.test import TestCase

@skipUnless(connection.vendor == "mysql", "MySQL tests")

class TestFeatures(TestCase):

    def test_supports_transactions(self):

        """

        All storage engines except MyISAM support transactions.

        """

        del connection.features.supports_transactions

        with mock.patch(

            "django.db.connection.features._mysql_storage_engine", "InnoDB"

        ):

            self.assertTrue(connection.features.supports_transactions)

        del connection.features.supports_transactions

        with mock.patch(

            "django.db.connection.features._mysql_storage_engine", "MyISAM"

        ):

            self.assertFalse(connection.features.supports_transactions)

        del connection.features.supports_transactions

    def test_skip_locked_no_wait(self):

        with mock.MagicMock() as _connection:

            _connection.mysql_version = (8, 0, 1)

            _connection.mysql_is_mariadb = False

            database_features = DatabaseFeatures(_connection)

            self.assertTrue(database_features.has_select_for_update_skip_locked)

            self.assertTrue(database_features.has_select_for_update_nowait)

        with mock.MagicMock() as _connection:

            _connection.mysql_version = (8, 0, 0)

            _connection.mysql_is_mariadb = False

            database_features = DatabaseFeatures(_connection)

            self.assertFalse(database_features.has_select_for_update_skip_locked)

            self.assertFalse(database_features.has_select_for_update_nowait)

    def test_allows_auto_pk_0(self):

        with mock.MagicMock() as _connection:

            _connection.sql_mode = {"NO_AUTO_VALUE_ON_ZERO"}

            database_features = DatabaseFeatures(_connection)

            self.assertIs(database_features.allows_auto_pk_0, True)