Query ft_billing aggregate for a month

tests/app/dao/test_ft_billing_dao.py

@@ -0,0 +1,24 @@
+from datetime import datetime
+from decimal import Decimal
+
+from app.dao.fact_billing_dao import fetch_annual_billing_by_month
+from tests.app.db import create_ft_billing, create_service, create_template
+
+
+def test_fetch_annual_billing_by_month(notify_db_session):
+    service = create_service()
+    template = create_template(service=service, template_type="email")
+    for i in range(1, 32):
+        record = create_ft_billing(bst_date='2018-01-{}'.format(i),
+                                   service=service,
+                                   template=template,
+                                   notification_type='email')
+
+    results, month = fetch_annual_billing_by_month(service_id=record.service_id,
+                                                   billing_month=datetime(2018, 1, 1),
+                                                   notification_type='email')
+
+    assert len(results) == 1
+    assert results[0] == (31, Decimal('31'), service.id, 'email', Decimal('0'), Decimal('1'), False)
+    assert month == datetime(2018, 1, 1)
+