A quiz where the teacher has set a time limit, a close date and "When time expires" to "Open attempts are submitted automatically".
1. As student, start a quiz attempt and answer some questions but not all, then log out of Moodle.
2. Wait until time limit has expired, which must be BEFORE the quiz cron runs (hourly) and before the close date has passed, 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".