A quiz where the teacher has set a time limit, a close date and "When time expires" to "the attempt is submitted automatically". The time limit must be long enough so that the close date can expire before the time limit.
1. As student, start a quiz attempt and answer some questions but not all, then log out of Moodle.
2. Wait until the close date has expired but the time limit has not, which must be BEFORE the quiz cron runs (hourly), then log back in as a teacher and make sure that the attempt is still shown as In-progress.
3. Then log in as a student, and go to the quiz info page. This should cause the quiz attempt to be automatically submitted, so you should see that your attempt is finished, with those questions you had answered graded.
4. Log in as a teacher and check that the attempt is no longer "In-progress".