Add formatted notification status to CSV

This commit makes the CSV download use the same language for failure
reasons as the frontend.

It also adds a test around this stuff, which was patchily tested before.

tests/app/test_utils.py

@@ -1,4 +1,8 @@
-from app.utils import email_safe
+import pytest
+from io import StringIO
+from app.utils import email_safe, generate_notifications_csv
+from csv import DictReader
+from freezegun import freeze_time
 
 
 def test_email_safe_return_dot_separated_email_domain():
@@ -6,3 +10,41 @@ def test_email_safe_return_dot_separated_email_domain():
     expected = 'some.service.withstuff.b123'
     actual = email_safe(test_name)
     assert actual == expected
+
+
+@pytest.mark.parametrize(
+    "status, template_type, expected_status",
+    [
+        ('sending', None, 'Sending'),
+        ('delivered', None, 'Delivered'),
+        ('failed', None, 'Failed'),
+        ('technical-failure', None, 'Technical failure'),
+        ('temporary-failure', 'email', 'Inbox not accepting messages right now'),
+        ('permanent-failure', 'email', 'Email address doesn’t exist'),
+        ('temporary-failure', 'sms', 'Phone not accepting messages right now'),
+        ('permanent-failure', 'sms', 'Phone number doesn’t exist')
+    ]
+)
+@freeze_time("2016-01-01 11:09:00.061258")
+def test_generate_csv_from_notifications(
+    app_,
+    service_one,
+    active_user_with_permissions,
+    mock_get_notifications,
+    status,
+    template_type,
+    expected_status
+):
+    with app_.test_request_context():
+        csv_content = generate_notifications_csv(
+            mock_get_notifications(
+                service_one['id'],
+                rows=1,
+                set_template_type=template_type,
+                set_status=status
+            )['notifications']
+        )
+
+    for row in DictReader(StringIO(csv_content)):
+        assert row['Time'] == 'Friday 01 January 2016 at 11:09'
+        assert row['Status'] == expected_status