test cleaning for the current state of things

tests/app/celery/test_nightly_tasks.py

@@ -15,7 +15,7 @@ from app.celery.nightly_tasks import (
     save_daily_notification_processing_time,
     timeout_notifications,
 )
-from app.models import EMAIL_TYPE, LETTER_TYPE, SMS_TYPE, FactProcessingTime
+from app.models import EMAIL_TYPE, SMS_TYPE, FactProcessingTime
 from tests.app.db import (
     create_job,
     create_notification,

tests/app/celery/test_research_mode_tasks.py

@@ -6,7 +6,6 @@ from flask import json
 
 from app.celery.research_mode_tasks import (
     HTTPError,
-    create_fake_letter_response_file,
     send_email_response,
     send_sms_response,
     ses_notification_callback,

tests/app/celery/test_tasks.py

@@ -44,8 +44,6 @@ from app.models import (
     SMS_TYPE,
     Job,
     Notification,
-    NotificationHistory,
-    ReturnedLetter,
 )
 from app.serialised_models import SerialisedService, SerialisedTemplate
 from app.utils import DATETIME_FORMAT
@@ -57,7 +55,6 @@ from tests.app.db import (
     create_job,
     create_letter_contact,
     create_notification,
-    create_notification_history,
     create_reply_to_email,
     create_service,
     create_service_inbound_api,