return fake "received_by_notify" status for letter notifications

created and sending aren't quite as helpful for letters, since their
journey through notify and our providers is so different to emails/sms.
So instead, we should return estimated_dispatch_date (in a future PR)
and the status should just read received_by_notify

app/models.py

@@ -797,6 +797,9 @@ NOTIFICATION_STATUS_TYPES_NON_BILLABLE = list(set(NOTIFICATION_STATUS_TYPES) - s
 
 NOTIFICATION_STATUS_TYPES_ENUM = db.Enum(*NOTIFICATION_STATUS_TYPES, name='notify_status_type')
 
+NOTIFICATION_STATUS_LETTER_RECEIVED = 'received_by_notify'
+NOTIFICATION_STATUS_LETTER_RECEIVED_PRETTY = 'Received by Notify'
+
 
 class NotificationStatusTypes(db.Model):
     __tablename__ = 'notification_status_types'
@@ -962,17 +965,29 @@ class Notification(db.Model):
                 'sent': 'Sent internationally'
             },
             'letter': {
-                'failed': 'Failed',
                 'technical-failure': 'Technical failure',
-                'temporary-failure': 'Temporary failure',
-                'permanent-failure': 'Permanent failure',
-                'delivered': 'Delivered',
-                'sending': 'Sending',
-                'created': 'Sending',
-                'sent': 'Delivered'
+                'sending': NOTIFICATION_STATUS_LETTER_RECEIVED_PRETTY,
+                'created': NOTIFICATION_STATUS_LETTER_RECEIVED_PRETTY,
             }
         }[self.template.template_type].get(self.status, self.status)
 
+    def get_letter_status(self):
+        """
+        Return the notification_status, as we should present for letters. The distinction between created and sending is
+        a bit more confusing for letters, not to mention that there's no concept of temporary or permanent failure yet.
+
+
+        """
+        # this should only ever be called for letter notifications - it makes no sense otherwise and I'd rather not
+        # get the two code flows mixed up at all
+        assert self.notification_type == LETTER_TYPE
+
+        if self.status == NOTIFICATION_CREATED or NOTIFICATION_SENDING:
+            return NOTIFICATION_STATUS_LETTER_RECEIVED
+        else:
+            # Currently can only be technical-failure
+            return status
+
     def serialize_for_csv(self):
         created_at_in_bst = convert_utc_to_bst(self.created_at)
         serialized = {
@@ -1007,7 +1022,7 @@ class Notification(db.Model):
             "line_6": None,
             "postcode": None,
             "type": self.notification_type,
-            "status": self.status,
+            "status": self.get_letter_status() if self.notification_type == LETTER_TYPE else self.status,
             "template": template_dict,
             "body": self.content,
             "subject": self.subject,

tests/app/test_model.py

@@ -116,8 +116,9 @@ def test_notification_for_csv_returns_correct_job_row_number(notify_db, notify_d
     ('sms', 'temporary-failure', 'Phone not accepting messages right now'),
     ('sms', 'permanent-failure', 'Phone number doesn’t exist'),
     ('sms', 'sent', 'Sent internationally'),
-    ('letter', 'permanent-failure', 'Permanent failure'),
-    ('letter', 'delivered', 'Delivered')
+    ('letter', 'created', 'Received by Notify'),
+    ('letter', 'sending', 'Received by Notify'),
+    ('letter', 'technical-failure', 'Technical failure')
 ])
 def test_notification_for_csv_returns_formatted_status(
     notify_db,