Fix incorrect chargeable_units column

This was added to migrate away from the vague "billing_units" field,
but without fixing the inconsistent data behind it:

- For emails and letters, "billing_units" was just the number sent.

- For SMS, "billing_units" really was the chargeable_units.

To avoid confusion we need two fields to represent the original mix
of data - this exposes "notifications_sent" in both APIs.

app/billing/billing_schemas.py

@@ -25,6 +25,7 @@ def serialize_ft_billing_remove_emails(rows):
             "cost": float(row.cost),
             "free_chargeable_units": row.free_chargeable_units,
             "charged_units": row.charged_units,
+            "notifications_sent": row.notifications_sent,
         }
         for row in rows
         if row.notification_type != 'email'
@@ -44,6 +45,7 @@ def serialize_ft_billing_yearly_totals(rows):
             "cost": float(row.cost),
             "free_chargeable_units": row.free_chargeable_units,
             "charged_units": row.charged_units,
+            "notifications_sent": row.notifications_sent,
         }
         for row in rows
     ]

app/dao/fact_billing_dao.py

@@ -202,7 +202,7 @@ def fetch_billing_totals_for_year(service_id, year):
             db.session.query(
                 func.sum(query.c.notifications_sent).label("notifications_sent"),
                 # TEMPORARY: while we switch to "chargeable units"
-                func.sum(query.c.chargeable_units).label("billable_units"),
+                func.sum(query.c.billable_units).label("billable_units"),
                 func.sum(query.c.chargeable_units).label("chargeable_units"),
                 query.c.rate.label("rate"),
                 query.c.notification_type.label("notification_type"),
@@ -241,7 +241,7 @@ def fetch_monthly_billing_for_year(service_id, year):
                 func.date_trunc('month', query.c.bst_date).cast(Date).label("month"),
                 func.sum(query.c.notifications_sent).label("notifications_sent"),
                 # TEMPORARY: while we switch to "chargeable units"
-                func.sum(query.c.chargeable_units).label("billable_units"),
+                func.sum(query.c.billable_units).label("billable_units"),
                 func.sum(query.c.chargeable_units).label("chargeable_units"),
                 query.c.rate.label("rate"),
                 query.c.postage.label("postage"),
@@ -275,7 +275,9 @@ def query_service_email_usage_for_year(service_id, year):
         FactBilling.bst_date,
         FactBilling.postage,  # should always be "none"
         FactBilling.notifications_sent,
-        FactBilling.notifications_sent.label("chargeable_units"),
+        # TEMPORARY: while we switch to "chargeable units"
+        FactBilling.notifications_sent.label("billable_units"),
+        FactBilling.billable_units.label("chargeable_units"),
         FactBilling.rate,
         FactBilling.notification_type,
         FactBilling.notifications_sent.label("charged_units"),
@@ -296,7 +298,9 @@ def query_service_letter_usage_for_year(service_id, year):
         FactBilling.bst_date,
         FactBilling.postage,
         FactBilling.notifications_sent,
-        FactBilling.notifications_sent.label("chargeable_units"),
+        # TEMPORARY: while we switch to "chargeable units"
+        FactBilling.notifications_sent.label("billable_units"),
+        FactBilling.billable_units.label("chargeable_units"),
         FactBilling.rate,
         FactBilling.notification_type,
         FactBilling.notifications_sent.label("charged_units"),
@@ -348,6 +352,8 @@ def query_service_sms_usage_for_year(service_id, year):
         FactBilling.bst_date,
         FactBilling.postage,  # should always be "none"
         FactBilling.notifications_sent,
+        # TEMPORARY: while we switch to "chargeable units"
+        chargeable_units.label("billable_units"),
         chargeable_units.label("chargeable_units"),
         FactBilling.rate,
         FactBilling.notification_type,

tests/app/billing/test_rest.py

@@ -178,6 +178,7 @@ def test_get_yearly_usage_by_monthly_from_ft_billing(admin_request, notify_db_se
     assert letter_row["cost"] == 9.9
     assert letter_row["free_chargeable_units"] == 0
     assert letter_row["charged_units"] == 30
+    assert letter_row["notifications_sent"] == 30
 
     assert sms_row["month"] == "April"
     assert sms_row["notification_type"] == "sms"
@@ -189,6 +190,7 @@ def test_get_yearly_usage_by_monthly_from_ft_billing(admin_request, notify_db_se
     assert sms_row["cost"] == 4.212
     assert sms_row["free_chargeable_units"] == 4
     assert sms_row["charged_units"] == 26
+    assert sms_row["notifications_sent"] == 30
 
 
 def set_up_yearly_data():
@@ -263,6 +265,7 @@ def test_get_yearly_billing_usage_summary_from_ft_billing(admin_request, notify_
     assert json_response[0]['cost'] == 0
     assert json_response[0]['free_chargeable_units'] == 0
     assert json_response[0]['charged_units'] == 275
+    assert json_response[0]['notifications_sent'] == 275
 
     assert json_response[1]['notification_type'] == 'letter'
     assert json_response[1]['billing_units'] == 275
@@ -272,6 +275,7 @@ def test_get_yearly_billing_usage_summary_from_ft_billing(admin_request, notify_
     assert json_response[1]['cost'] == 90.75
     assert json_response[1]['free_chargeable_units'] == 0
     assert json_response[1]['charged_units'] == 275
+    assert json_response[1]['notifications_sent'] == 275
 
     assert json_response[2]['notification_type'] == 'sms'
     assert json_response[2]['billing_units'] == 825
@@ -281,3 +285,4 @@ def test_get_yearly_billing_usage_summary_from_ft_billing(admin_request, notify_
     assert json_response[2]['cost'] == 13.3002
     assert json_response[2]['free_chargeable_units'] == 4
     assert json_response[2]['charged_units'] == 821
+    assert json_response[2]['notifications_sent'] == 825

tests/app/dao/test_ft_billing_dao.py

@@ -489,7 +489,7 @@ def test_fetch_monthly_billing_for_year_variable_rates(notify_db_session):
     assert results[1].notification_type == 'letter'
     assert results[1].notifications_sent == 1
     assert results[1].billable_units == 1
-    assert results[1].chargeable_units == 1
+    assert results[1].chargeable_units == 2
     assert results[1].rate == Decimal('0.36')
     assert results[1].cost == Decimal('0.36')
     assert results[1].free_chargeable_units == 0
@@ -614,7 +614,7 @@ def test_fetch_billing_totals_for_year_variable_rates(notify_db_session):
     assert results[1].notification_type == 'letter'
     assert results[1].notifications_sent == 1
     assert results[1].billable_units == 1
-    assert results[1].chargeable_units == 1
+    assert results[1].chargeable_units == 2
     assert results[1].rate == Decimal('0.36')
     assert results[1].cost == Decimal('0.36')
     assert results[1].free_chargeable_units == 0