SessionMiddleware tests leaving Session objects in database

[Matt Leach]

Currently with default settings several tests in contrib.sessions.SessionMiddlewareTests leave Session objects remaining in the database.

This can be seen by adding a tearDown method:

class SessionMiddlewareTests(unittest.TestCase):
    
    def tearDown(self):
        print "Session count:", len(Session.objects.all())

This results in the following output:

$ ./manage.py test django.contrib.sessions.tests.SessionMiddlewareTests -v 3

...

test_httponly_session_cookie (django.contrib.sessions.tests.SessionMiddlewareTests) ... Session count: 1
ok
test_no_httponly_session_cookie (django.contrib.sessions.tests.SessionMiddlewareTests) ... Session count: 2
ok
test_secure_session_cookie (django.contrib.sessions.tests.SessionMiddlewareTests) ... Session count: 3
ok
test_session_delete_on_end (django.contrib.sessions.tests.SessionMiddlewareTests) ... Session count: 3
ok
test_session_save_on_500 (django.contrib.sessions.tests.SessionMiddlewareTests) ... Session count: 4
ok

----------------------------------------------------------------------
Ran 5 tests in 0.011s

OK

Currently this does not result in failing tests when the test suite is run but it could lead to issues with tests such as contrib.sessions.DatabaseSessionTests.test_clearsessions_command:

class DatabaseSessionTests(SessionTestsMixin, TestCase):

    backend = DatabaseSession

    ...

    @override_settings(SESSION_ENGINE="django.contrib.sessions.backends.db")
    def test_clearsessions_command(self):
        """
        Test clearsessions command for clearing expired sessions.
        """
        self.assertEqual(0, Session.objects.count())

which would fail if run immediately after the SessionMiddleware tests.

I would suggest changing the SessionMiddlewareTests class to inherit from django.test.TestCase rather than unittest.TestCase which will ensure the database is flushed after the tests run.

[Simon Charette]

This change makes sense to me, can you open a PR with the required change?

[Matt Leach]

Will do

[Simon Charette <charette.s@…>]

In 55c76f4e3bab74c8544b72d11a99e94a1c2cfbce:

Fixed #24223 -- Prevented a session test from leaking.

[Simon Charette <charette.s@…>]

In 7b92acea7055c6b39207a813b52e683a3672e467:

[1.8.x] Fixed #24223 -- Prevented a session test from leaking.

Backport of 55c76f4e3bab74c8544b72d11a99e94a1c2cfbce from master