Fix bug in organisation report for its services and usages.

If a service has not sent any SMS for the financial year the free allowance was showing up as 0 rather than the number in annual billing. The query has been updated to use an outer join so that the free allow will be returned when there is no ft_billing.

There is a potential performance enhancement to only return the data for the services of the organisation in the `fetch_sms_free_allowance_remainder_until_date` subquery. I will investigate in a subsequent PR.

app/dao/fact_billing_dao.py

@@ -599,7 +599,7 @@ def fetch_sms_billing_for_organisation(organisation_id, start_date, end_date):
     # ASSUMPTION: AnnualBilling has been populated for year.
     allowance_left_at_start_date_query = fetch_sms_free_allowance_remainder_until_date(start_date).subquery()
 
-    sms_billable_units = func.sum(FactBilling.billable_units * FactBilling.rate_multiplier)
+    sms_billable_units = func.coalesce(func.sum(FactBilling.billable_units * FactBilling.rate_multiplier), 0)
 
     # subtract sms_billable_units units accrued since report's start date to get up-to-date
     # allowance remainder
@@ -614,23 +614,25 @@ def fetch_sms_billing_for_organisation(organisation_id, start_date, end_date):
     query = db.session.query(
         Service.name.label("service_name"),
         Service.id.label("service_id"),
-        allowance_left_at_start_date_query.c.free_sms_fragment_limit,
-        FactBilling.rate.label('sms_rate'),
-        sms_allowance_left.label("sms_remainder"),
-        sms_billable_units.label('sms_billable_units'),
-        chargeable_sms.label("chargeable_billable_sms"),
-        sms_cost.label('sms_cost'),
+        func.coalesce(allowance_left_at_start_date_query.c.free_sms_fragment_limit, 0).label('free_sms_fragment_limit'),
+        func.coalesce(FactBilling.rate, 0).label('sms_rate'),
+        func.coalesce(sms_allowance_left, 0).label("sms_remainder"),
+        func.coalesce(sms_billable_units, 0).label('sms_billable_units'),
+        func.coalesce(chargeable_sms, 0).label("chargeable_billable_sms"),
+        func.coalesce(sms_cost, 0).label('sms_cost'),
         Service.active.label("active")
     ).select_from(
         Service
     ).outerjoin(
         allowance_left_at_start_date_query, Service.id == allowance_left_at_start_date_query.c.service_id
-    ).join(
-        FactBilling, FactBilling.service_id == Service.id,
+    ).outerjoin(
+        FactBilling, and_(
+            Service.id == FactBilling.service_id,
+            FactBilling.bst_date >= start_date,
+            FactBilling.bst_date < end_date,
+            FactBilling.notification_type == SMS_TYPE,
+        )
     ).filter(
-        FactBilling.bst_date >= start_date,
-        FactBilling.bst_date <= end_date,
-        FactBilling.notification_type == SMS_TYPE,
         Service.organisation_id == organisation_id,
         Service.restricted.is_(False)
     ).group_by(

tests/app/dao/test_ft_billing_dao.py

@@ -736,7 +736,7 @@ def test_fetch_usage_year_for_organisation(notify_db_session):
                       notifications_sent=1100)
     results = fetch_usage_year_for_organisation(fixtures["org_1"].id, 2019)
 
-    assert len(results) == 2
+    assert len(results) == 3
     first_row = results[str(fixtures["service_1_sms_and_letter"].id)]
     assert first_row['service_id'] == fixtures["service_1_sms_and_letter"].id
     assert first_row['service_name'] == fixtures["service_1_sms_and_letter"].name
@@ -757,6 +757,16 @@ def test_fetch_usage_year_for_organisation(notify_db_session):
     assert second_row['letter_cost'] == 0
     assert second_row['emails_sent'] == 1100
 
+    third_row = results[str(fixtures["service_with_out_ft_billing_this_year"].id)]
+    assert third_row['service_id'] == fixtures["service_with_out_ft_billing_this_year"].id
+    assert third_row['service_name'] == fixtures["service_with_out_ft_billing_this_year"].name
+    assert third_row['free_sms_limit'] == 10
+    assert third_row['sms_remainder'] == 10
+    assert third_row['chargeable_billable_sms'] == 0
+    assert third_row['sms_cost'] == 0
+    assert third_row['letter_cost'] == 0
+    assert third_row['emails_sent'] == 0
+
 
 def test_fetch_usage_year_for_organisation_populates_ft_billing_for_today(notify_db_session):
     create_letter_rate(start_date=datetime.utcnow() - timedelta(days=1))

tests/app/db.py

@@ -1054,6 +1054,19 @@ def set_up_usage_data(start_date):
     )
     create_ft_billing(bst_date=one_week_later, template=sms_template_2, billable_unit=2, rate=0.11)
 
+    # service without ft_billing this year
+    service_with_out_ft_billing_this_year = create_service(
+        service_name='f - without ft_billing',
+        purchase_order_number="sms purchase order number",
+        billing_contact_names="sms billing contact names",
+        billing_contact_email_addresses="sms@billing.contact email@addresses.gov.uk",
+        billing_reference="sms billing reference"
+    )
+    create_annual_billing(
+        service_id=service_with_out_ft_billing_this_year.id, free_sms_fragment_limit=10, financial_year_start=year
+    )
+    dao_add_service_to_organisation(service=service_with_out_ft_billing_this_year, organisation_id=org_1.id)
+
     # dictionary with services and orgs to return
     return {
         "org_1": org_1,
@@ -1065,6 +1078,7 @@ def set_up_usage_data(start_date):
         "service_with_letters_without_org": service_with_letters_without_org,
         "service_with_sms_without_org": service_with_sms_without_org,
         "service_with_sms_within_allowance": service_with_sms_within_allowance,
+        "service_with_out_ft_billing_this_year": service_with_out_ft_billing_this_year,
     }