Don’t show the postage when validation has failed

The postage covers up some of the letter, so it can hide the problem. It
also implies that the letter has been put in an envelope, which will
never happen if it fails validation.

This matches what we do for uploaded letters.

app/main/views/notifications.py

@@ -78,7 +78,10 @@ def view_notification(service_id, notification_id):
         page_count = get_page_count_for_letter(notification['template'], values=personalisation)
 
     if notification.get('postage'):
-        notification['template']['postage'] = notification['postage']
+        if notification["status"] == "validation-failed":
+            notification['template']['postage'] = None
+        else:
+            notification['template']['postage'] = notification['postage']
     template = get_template(
         notification['template'],
         current_service,

tests/app/main/views/test_notifications.py

@@ -405,6 +405,7 @@ def test_notification_page_shows_validation_failed_precompiled_letter(
     assert not page.select('p.notification-status')
 
     assert page.select_one('main img')['src'].endswith('.png?page=1')
+    assert not page.select('.letter-postage')
 
 
 @pytest.mark.parametrize('notification_status, expected_message', (