Allow users to set postage per precompiled letter

app/notifications/process_letter_notifications.py

@@ -20,6 +20,7 @@ def create_letter_notification(letter_data, template, api_key, status, reply_to_
         client_reference=letter_data.get('reference'),
         status=status,
         reply_to_text=reply_to_text,
-        billable_units=billable_units
+        billable_units=billable_units,
+        postage=letter_data.get('postage')
     )
     return notification

app/notifications/process_notifications.py

@@ -75,7 +75,8 @@ def persist_notification(
     created_by_id=None,
     status=NOTIFICATION_CREATED,
     reply_to_text=None,
-    billable_units=None
+    billable_units=None,
+    postage=None
 ):
     notification_created_at = created_at or datetime.utcnow()
     if not notification_id:
@@ -112,6 +113,9 @@ def persist_notification(
     elif notification_type == EMAIL_TYPE:
         notification.normalised_to = format_email_address(notification.to)
     elif notification_type == LETTER_TYPE:
+        if postage:
+            notification.postage = postage
+        else:
             template = dao_get_template_by_id(template_id, template_version)
             if service.has_permission(CHOOSE_POSTAGE) and template.postage:
                 notification.postage = template.postage

app/v2/notifications/notification_schemas.py

@@ -239,7 +239,8 @@ post_precompiled_letter_request = {
     "title": "POST v2/notifications/letter",
     "properties": {
         "reference": {"type": "string"},
-        "content": {"type": "string"}
+        "content": {"type": "string"},
+        "postage": {"type": "string"}
     },
     "required": ["reference", "content"],
     "additionalProperties": False

tests/app/v2/notifications/test_post_letter_notifications.py

@@ -469,16 +469,27 @@ def test_post_precompiled_letter_with_invalid_base64(client, notify_user, mocker
     assert not Notification.query.first()
 
 
-@pytest.mark.parametrize('postage', ['first', 'second'])
-def test_post_precompiled_letter_notification_returns_201(client, notify_user, mocker, postage):
+@pytest.mark.parametrize('service_postage, notification_postage, expected_postage', [
+    ('second', 'second', 'second'),
+    ('second', 'first', 'first'),
+    ('second', None, 'second'),
+    ('first', 'first', 'first'),
+    ('first', 'second', 'second'),
+    ('first', None, 'first'),
+])
+def test_post_precompiled_letter_notification_returns_201(
+    client, notify_user, mocker, service_postage, notification_postage, expected_postage
+):
     sample_service = create_service(service_permissions=['letter', 'precompiled_letter'])
-    sample_service.postage = postage
+    sample_service.postage = service_postage
     s3mock = mocker.patch('app.v2.notifications.post_notifications.upload_letter_pdf')
     mocker.patch('app.celery.letters_pdf_tasks.notify_celery.send_task')
     data = {
         "reference": "letter-reference",
         "content": "bGV0dGVyLWNvbnRlbnQ="
     }
+    if notification_postage:
+        data["postage"] = notification_postage
     auth_header = create_authorization_header(service_id=sample_service.id)
     response = client.post(
         path="v2/notifications/letter",
@@ -493,10 +504,10 @@ def test_post_precompiled_letter_notification_returns_201(client, notify_user, m
 
     assert notification.billable_units == 0
     assert notification.status == NOTIFICATION_PENDING_VIRUS_CHECK
-    assert notification.postage == postage
+    assert notification.postage == expected_postage
 
     notification_history = NotificationHistory.query.one()
-    assert notification_history.postage == postage
+    assert notification_history.postage == expected_postage
 
     resp_json = json.loads(response.get_data(as_text=True))
     assert resp_json == {'id': str(notification.id), 'reference': 'letter-reference'}