Create a quiz with one essay question. Set the review options to turn everything off except for the 'The attempt' checkboxes. Attempt the quiz as a student. As teacher/admin manually grade that question, putting in the comment "This should not be visible yet". As student, review your attempt. Verify that the "This should not be visible yet" text does not appear. As teacher, edit the quiz settings, and turn on all the 'Specific feedback' review options. As student, review your attempt again. Verify that the "This should not be visible yet" text appears now.