Fix the logic gettting the rates for a financial year.

The is_between_end_date_exclusive is a bit funny.
Perhaps the better way to handle it is to make the function is_between but change the financial year function return an enddate that is one millisecond less. That way we can always use the between logic and it will be easier to use.

app/dao/notification_usage_dao.py

@@ -1,7 +1,7 @@
 from datetime import datetime
 
 from sqlalchemy import Float, Integer
-from sqlalchemy import func, case, cast
+from sqlalchemy import func, case, cast, desc, between
 from sqlalchemy import literal_column
 
 from app import db
@@ -103,8 +103,25 @@ def sms_yearly_billing_data_query(rate, service_id, start_date, end_date):
 
 
 def get_rates_for_year(start_date, end_date, notification_type):
-    return Rate.query.filter(Rate.valid_from >= start_date, Rate.valid_from < end_date,
+    rates = Rate.query.filter(Rate.notification_type == notification_type).order_by(Rate.valid_from).all()
-                             Rate.notification_type == notification_type).order_by(Rate.valid_from).all()
+    results = []
+    for current_rate, current_rate_expiry_date in zip(rates, rates[1:]):
+        if is_between_end_date_exclusive(current_rate.valid_from, start_date, end_date) or \
+                is_between_end_date_exclusive(current_rate_expiry_date.valid_from, start_date, end_date):
+            results.append(current_rate)
+
+    if is_between_end_date_exclusive(rates[-1].valid_from, start_date, end_date):
+        results.append(rates[-1])
+
+    if not results:
+        if start_date >= rates[-1].valid_from:
+            results.append(rates[-1])
+
+    return results
+
+
+def is_between_end_date_exclusive(date, start_date, end_date):
+    return start_date <= date < end_date
 
 
 def sms_billing_data_per_month_query(rate, service_id, start_date, end_date):

tests/app/dao/test_notification_usage_dao.py

@@ -1,6 +1,7 @@
 import uuid
 from datetime import datetime
 
+from app.dao.date_util import get_financial_year
 from app.dao.notification_usage_dao import (get_rates_for_year, get_yearly_billing_data,
                                             get_monthly_billing_data)
 from app.models import Rate
@@ -9,20 +10,64 @@ from tests.app.db import create_notification
 
 def test_get_rates_for_year(notify_db, notify_db_session):
     set_up_rate(notify_db, datetime(2016, 4, 1), 1.50)
+    set_up_rate(notify_db, datetime(2016, 9, 1), 1.60)
     set_up_rate(notify_db, datetime(2017, 6, 1), 1.75)
-    rates = get_rates_for_year(datetime(2016, 4, 1), datetime(2017, 3, 31), 'sms')
+    rates = get_rates_for_year(datetime(2016, 3, 31), datetime(2017, 3, 31), 'sms')
-    assert len(rates) == 1
+    assert len(rates) == 2
     assert datetime.strftime(rates[0].valid_from, '%Y-%m-%d %H:%M:%S') == "2016-04-01 00:00:00"
     assert rates[0].rate == 1.50
-    rates = get_rates_for_year(datetime(2017, 4, 1), datetime(2018, 3, 31), 'sms')
+    assert datetime.strftime(rates[1].valid_from, '%Y-%m-%d %H:%M:%S') == "2016-09-01 00:00:00"
-    assert len(rates) == 1
+    assert rates[1].rate == 1.6
+    start_date, end_date = get_financial_year(2017)
+    rates_2017 = get_rates_for_year(start_date, end_date, 'sms')
+    assert len(rates_2017) == 2
+    assert datetime.strftime(rates_2017[0].valid_from, '%Y-%m-%d %H:%M:%S') == "2016-09-01 00:00:00"
+    assert rates_2017[0].rate == 1.60
+    assert datetime.strftime(rates_2017[1].valid_from, '%Y-%m-%d %H:%M:%S') == "2017-06-01 00:00:00"
+    assert rates_2017[1].rate == 1.75
+
+
+def test_get_rates_for_year_in_the_future(notify_db, notify_db_session):
+    set_up_rate(notify_db, datetime(2016, 4, 1), 1.50)
+    set_up_rate(notify_db, datetime(2017, 6, 1), 1.75)
+    start_date, end_date = get_financial_year(2018)
+    rates = get_rates_for_year(start_date, end_date, 'sms')
     assert datetime.strftime(rates[0].valid_from, '%Y-%m-%d %H:%M:%S') == "2017-06-01 00:00:00"
     assert rates[0].rate == 1.75
 
 
+def test_get_rates_for_year_returns_empty_list_if_year_is_before_earliest_rate(notify_db, notify_db_session):
+    set_up_rate(notify_db, datetime(2016, 4, 1), 1.50)
+    set_up_rate(notify_db, datetime(2017, 6, 1), 1.75)
+    start_date, end_date = get_financial_year(2015)
+    rates = get_rates_for_year(start_date, end_date, 'sms')
+    assert rates == []
+
+
+def test_get_rates_for_year_early_rate(notify_db, notify_db_session):
+    set_up_rate(notify_db, datetime(2015, 6, 1), 1.40)
+    set_up_rate(notify_db, datetime(2016, 6, 1), 1.50)
+    set_up_rate(notify_db, datetime(2016, 9, 1), 1.60)
+    set_up_rate(notify_db, datetime(2017, 6, 1), 1.75)
+    start_date, end_date = get_financial_year(2016)
+    rates = get_rates_for_year(start_date, end_date, 'sms')
+    assert len(rates) == 3
+
+
+def test_get_rates_for_year_edge_case(notify_db, notify_db_session):
+    set_up_rate(notify_db, datetime(2016, 3, 31, 23, 00), 1.50)
+    set_up_rate(notify_db, datetime(2017, 3, 31, 23, 00), 1.75)
+    start_date, end_date = get_financial_year(2016)
+    rates = get_rates_for_year(start_date, end_date, 'sms')
+    assert len(rates) == 1
+    assert datetime.strftime(rates[0].valid_from, '%Y-%m-%d %H:%M:%S') == "2016-03-31 23:00:00"
+    assert rates[0].rate == 1.50
+
+
 def test_get_yearly_billing_data(notify_db, notify_db_session, sample_template, sample_email_template):
     set_up_rate(notify_db, datetime(2016, 4, 1), 1.40)
     set_up_rate(notify_db, datetime(2016, 6, 1), 1.58)
+    set_up_rate(notify_db, datetime(2017, 6, 1), 1.65)
     # previous year
     create_notification(template=sample_template, created_at=datetime(2016, 3, 31), sent_at=datetime(2016, 3, 31),
                         status='sending', billable_units=1)
@@ -131,6 +176,7 @@ def test_get_monthly_billing_data_with_multiple_rates(notify_db, notify_db_sessi
                                                       sample_email_template):
     set_up_rate(notify_db, datetime(2016, 4, 1), 1.40)
     set_up_rate(notify_db, datetime(2016, 6, 5), 1.75)
+    set_up_rate(notify_db, datetime(2017, 7, 5), 1.80)
     # previous year
     create_notification(template=sample_template, created_at=datetime(2016, 3, 31), sent_at=datetime(2016, 3, 31),
                         status='sending', billable_units=1)