from django.contrib.auth.middleware import AuthenticationMiddleware
from django.contrib.auth.models import User
from django.http import HttpRequest, HttpResponse
from django.test import TestCase


class TestAuthenticationMiddleware(TestCase):
    def setUp(self):
        self.user = User.objects.create_user('test_user', 'test@example.com', 'test_password')
        self.middleware = AuthenticationMiddleware(lambda req: HttpResponse())
        self.client.force_login(self.user)
        self.request = HttpRequest()
        self.request.session = self.client.session

    def test_no_password_change_doesnt_invalidate_session(self):
        self.request.session = self.client.session
        self.middleware(self.request)
        self.assertIsNotNone(self.request.user)
        self.assertFalse(self.request.user.is_anonymous)

    def test_changed_password_invalidates_session(self):
        # After password change, user should be anonymous
        self.user.set_password('new_password')
        self.user.save()
        self.middleware(self.request)
        self.assertIsNotNone(self.request.user)
        self.assertTrue(self.request.user.is_anonymous)
        # session should be flushed
        self.assertIsNone(self.request.session.session_key)

    def test_no_session(self):
        msg = (
            "The Django authentication middleware requires session middleware "
            "to be installed. Edit your MIDDLEWARE setting to insert "
            "'django.contrib.sessions.middleware.SessionMiddleware' before "
            "'django.contrib.auth.middleware.AuthenticationMiddleware'."
        )
        with self.assertRaisesMessage(AssertionError, msg):
            self.middleware(HttpRequest())