Tests/quizzes can remain open for a maximum of 6 hours before the session expires.
If the test will take longer than 6 hours to complete, instructors can make the test/quiz resumable from the Settings tab. With this setting enabled, students are able to exit the test/quiz their progress saved and resume it at a later time.
If a test/quiz session is open for over 6 hours, students will see a message that states, "The test/quiz that you are attempting to resume has expired. In order to continue, you must exist the test/quiz and resume progress (please note: some quizzes are not resumable). Your previous work has been saved."
When students select Close & Exit Test/Quiz from this message, they'll be taken back to the Test/Quiz tab in order to resume the test.