Add service_email_reply_to DAO with an upsert method

tests/app/dao/test_service_email_reply_to_dao.py

@@ -0,0 +1,41 @@
+from app.dao.service_email_reply_to_dao import (
+    create_or_update_email_reply_to,
+    dao_get_reply_to_by_service_id
+)
+from app.models import ServiceEmailReplyTo
+from tests.app.db import create_reply_to_email, create_service
+
+
+def test_create_or_update_email_reply_to_does_not_create_another_entry(notify_db_session):
+    service = create_service()
+    create_reply_to_email(service, 'test@mail.com')
+
+    create_or_update_email_reply_to(service.id, 'different@mail.com')
+
+    reply_to = dao_get_reply_to_by_service_id(service.id)
+
+    assert ServiceEmailReplyTo.query.count() == 1
+
+
+def test_create_or_update_email_reply_to_updates_existing_entry(notify_db_session):
+    service = create_service()
+    create_reply_to_email(service, 'test@mail.com')
+
+    create_or_update_email_reply_to(service.id, 'different@mail.com')
+
+    reply_to = dao_get_reply_to_by_service_id(service.id)
+
+    assert reply_to.service.id == service.id
+    assert reply_to.email_address == 'different@mail.com'
+
+
+def test_create_or_update_email_reply_to_creates_new_entry(notify_db_session):
+    service = create_service()
+
+    create_or_update_email_reply_to(service.id, 'test@mail.com')
+
+    reply_to = dao_get_reply_to_by_service_id(service.id)
+
+    assert ServiceEmailReplyTo.query.count() == 1
+    assert reply_to.service.id == service.id
+    assert reply_to.email_address == 'test@mail.com'