Add delivery status endpoint

tests/app/status/test_delivery_status.py

@@ -0,0 +1,34 @@
+import json
+
+from datetime import (
+    datetime,
+    timedelta
+)
+
+
+def test_get_delivery_status_all_ok(notify_api, notify_db):
+    with notify_api.test_request_context():
+        with notify_api.test_client() as client:
+            path = '/_delivery_status'
+            response = client.get(path)
+            assert response.status_code == 200
+            resp_json = json.loads(response.get_data(as_text=True))
+            assert resp_json['status'] == 'ok'
+            assert resp_json['message'] == '0 notifications in sending state over 5 minutes'
+
+
+def test_get_delivery_status_with_undelivered_notification(notify_api, notify_db, sample_notification):
+
+    more_than_five_mins_ago = datetime.now() - timedelta(minutes=10)
+    sample_notification.created_at = more_than_five_mins_ago
+    notify_db.session.add(sample_notification)
+    notify_db.session.commit()
+
+    with notify_api.test_request_context():
+        with notify_api.test_client() as client:
+            path = '/_delivery_status'
+            response = client.get(path)
+            assert response.status_code == 500
+            resp_json = json.loads(response.get_data(as_text=True))
+            assert resp_json['status'] == 'error'
+            assert resp_json['message'] == '1 notifications in sending state over 5 minutes'