Allow filtering of billing info by financial year

We already filter the usage-by-month query by financial year. When we
show the total usage for a service, we should be able to filter this
by financial year.

Then, when the two lots of data are put side by side, it all adds up.

app/dao/provider_statistics_dao.py

@@ -8,15 +8,21 @@ from app.models import (
     NOTIFICATION_STATUS_TYPES_BILLABLE,
     KEY_TYPE_TEST
 )
+from app.dao.notifications_dao import get_financial_year
 
 
-def get_fragment_count(service_id):
+def get_fragment_count(service_id, year=None):
     shared_filters = [
         NotificationHistory.service_id == service_id,
         NotificationHistory.status.in_(NOTIFICATION_STATUS_TYPES_BILLABLE),
         NotificationHistory.key_type != KEY_TYPE_TEST
     ]
 
+    if year:
+        shared_filters.append(NotificationHistory.created_at.between(
+            *get_financial_year(year)
+        ))
+
     sms_count = db.session.query(
         func.sum(NotificationHistory.billable_units)
     ).filter(

app/service/rest.py

@@ -190,7 +190,13 @@ def remove_user_from_service(service_id, user_id):
 
 @service_blueprint.route('/<uuid:service_id>/fragment/aggregate_statistics')
 def get_service_provider_aggregate_statistics(service_id):
-    return jsonify(data=get_fragment_count(service_id))
+    year = request.args.get('year')
+    if year is not None:
+        try:
+            year = int(year)
+        except ValueError:
+            raise InvalidRequest('Year must be a number', status_code=400)
+    return jsonify(data=get_fragment_count(service_id, year=year))
 
 
 # This is placeholder get method until more thought

tests/app/dao/test_provider_statistics_dao.py

@@ -2,6 +2,7 @@ from datetime import datetime
 import uuid
 
 import pytest
+from freezegun import freeze_time
 
 from app.models import NotificationHistory, KEY_TYPE_NORMAL, KEY_TYPE_TEAM, KEY_TYPE_TEST, NOTIFICATION_STATUS_TYPES
 from app.dao.provider_statistics_dao import get_fragment_count
@@ -35,6 +36,20 @@ def test_get_fragment_count_filters_on_service_id(notify_db, sample_template, se
     assert get_fragment_count(service_2.id)['sms_count'] == 0
 
 
+@pytest.mark.parametrize('creation_time, expected_count', [
+    ('2000-03-31 22:59:59', 0),  # before the start of the year
+    ('2000-04-01 00:00:00', 1),  # after the start of the year
+    ('2001-03-31 22:59:59', 1),  # before the end of the year
+    ('2001-04-01 00:00:00', 0),  # after the end of the year
+])
+def test_get_fragment_count_filters_on_year(
+    notify_db, sample_template, creation_time, expected_count
+):
+    with freeze_time(creation_time):
+        noti_hist(notify_db, sample_template)
+    assert get_fragment_count(sample_template.service_id, year=2000)['sms_count'] == expected_count
+
+
 def test_get_fragment_count_sums_billable_units_for_sms(notify_db, sample_template):
     noti_hist(notify_db, sample_template, billable_units=1)
     noti_hist(notify_db, sample_template, billable_units=2)