Add a more accurate missing notifications message

Notifications could be missing because:
- none have been created yet
- they’ve been deleted

This commit adds separate error messages for each case, rather than a
less helpful generic one.

app/main/views/jobs.py

@@ -480,6 +480,7 @@ def get_job_partials(job, template):
             job=job,
             template=template,
             template_version=job['template_version'],
+            service_data_retention_days=service_data_retention_days,
         ),
         'status': render_template(
             'partials/jobs/status.html',

app/templates/partials/jobs/notifications.html

@@ -47,7 +47,7 @@
         notifications,
         caption=uploaded_file_name,
         caption_visible=False,
-        empty_message="No messages to show",
+        empty_message='These messages have been deleted because they were sent more than {} days ago'.format(service_data_retention_days) if job.job_status == 'finished' else 'No messages to show yet…',
         field_headings=[
           'Recipient',
           'Status'

tests/app/main/views/test_jobs.py

@@ -314,7 +314,7 @@ def test_should_show_job_without_notifications(
         job_id=fake_uuid,
     )
     assert page.select_one('p.hint').text.strip() == 'Report is 50% complete…'
-    assert page.select_one('tbody').text.strip() == 'No messages to show'
+    assert page.select_one('tbody').text.strip() == 'No messages to show yet…'
 
 
 def test_should_show_old_job(
@@ -335,7 +335,9 @@ def test_should_show_old_job(
     )
     assert not page.select('p.hint')
     assert not page.select('a[download]')
-    assert page.select_one('tbody').text.strip() == 'No messages to show'
+    assert page.select_one('tbody').text.strip() == (
+        'These messages have been deleted because they were sent more than 7 days ago'
+    )
 
 
 @freeze_time("2016-01-01 11:09:00.061258")