use db models instead of tuples when referring to rate objects

makes it less confusing

app/dao/fact_billing_dao.py

@@ -209,10 +209,8 @@ def fetch_billing_data_for_day(process_day, service_id=None):
 
 
 def get_rates_for_billing():
-    non_letter_rates = [(r.notification_type, r.valid_from, r.rate) for r in
-                        Rate.query.order_by(desc(Rate.valid_from)).all()]
-    letter_rates = [(r.start_date, r.crown, r.sheet_count, r.rate, r.post_class) for r in
-                    LetterRate.query.order_by(desc(LetterRate.start_date)).all()]
+    non_letter_rates = Rate.query.order_by(desc(Rate.valid_from)).all()
+    letter_rates = LetterRate.query.order_by(desc(LetterRate.start_date)).all()
     return non_letter_rates, letter_rates
 
 
@@ -234,11 +232,22 @@ def get_rate(
         if letter_page_count == 0:
             return 0
         return next(
-            r[3] for r in letter_rates if date >= r[0] and crown == r[1]
-            and letter_page_count == r[2] and post_class == r[4]
+            r.rate
+            for r in letter_rates if (
+                date >= r.start_date and
+                crown == r.crown and
+                letter_page_count == r.sheet_count and
+                post_class == r.post_class
+            )
         )
     elif notification_type == SMS_TYPE:
-        return next(r[2] for r in non_letter_rates if notification_type == r[0] and date >= r[1])
+        return next(
+            r.rate
+            for r in non_letter_rates if (
+                notification_type == r.notification_type and
+                date >= r.valid_from
+            )
+        )
     else:
         return 0
 

tests/app/celery/test_reporting_tasks.py

@@ -14,10 +14,8 @@ from app.models import (
     EMAIL_TYPE,
     SMS_TYPE, FactNotificationStatus
 )
-from app.models import LetterRate, Rate
-from app import db
 
-from tests.app.db import create_service, create_template, create_notification
+from tests.app.db import create_service, create_template, create_notification, create_rate, create_letter_rate
 
 
 def mocker_get_rate(
@@ -322,38 +320,26 @@ def test_create_nightly_billing_consolidate_from_3_days_delta(
 
 
 def test_get_rate_for_letter_latest(notify_db_session):
-    non_letter_rates = [(r.notification_type, r.valid_from, r.rate) for r in
-                        Rate.query.order_by(desc(Rate.valid_from)).all()]
-
     # letter rates should be passed into the get_rate function as a tuple of start_date, crown, sheet_count,
     # rate and post_class
-    new_letter_rate = (datetime(2017, 12, 1), True, 1, Decimal(0.33), 'second')
-    old_letter_rate = (datetime(2016, 12, 1), True, 1, Decimal(0.30), 'second')
-    letter_rates = [new_letter_rate, old_letter_rate]
+    new = create_letter_rate(datetime(2017, 12, 1), crown=True, sheet_count=1, rate=0.33, post_class='second')
+    old = create_letter_rate(datetime(2016, 12, 1), crown=True, sheet_count=1, rate=0.30, post_class='second')
+    letter_rates = [new, old]
 
-    rate = get_rate(non_letter_rates, letter_rates, LETTER_TYPE, datetime(2018, 1, 1), True, 1)
+    rate = get_rate([], letter_rates, LETTER_TYPE, datetime(2018, 1, 1), True, 1)
     assert rate == Decimal(0.33)
 
 
 def test_get_rate_for_sms_and_email(notify_db_session):
-    sms_rate = Rate(valid_from=datetime(2017, 12, 1),
-                    rate=Decimal(0.15),
-                    notification_type=SMS_TYPE)
-    db.session.add(sms_rate)
-    email_rate = Rate(valid_from=datetime(2017, 12, 1),
-                      rate=Decimal(0),
-                      notification_type=EMAIL_TYPE)
-    db.session.add(email_rate)
+    non_letter_rates = [
+        create_rate(datetime(2017, 12, 1), 0.15, SMS_TYPE)
+        create_rate(datetime(2017, 12, 1), 0, EMAIL_TYPE)
+    ]
 
-    non_letter_rates = [(r.notification_type, r.valid_from, r.rate) for r in
-                        Rate.query.order_by(desc(Rate.valid_from)).all()]
-    letter_rates = [(r.start_date, r.crown, r.sheet_count, r.rate) for r in
-                    LetterRate.query.order_by(desc(LetterRate.start_date)).all()]
-
-    rate = get_rate(non_letter_rates, letter_rates, SMS_TYPE, datetime(2018, 1, 1))
+    rate = get_rate(non_letter_rates, [], SMS_TYPE, datetime(2018, 1, 1))
     assert rate == Decimal(0.15)
 
-    rate = get_rate(non_letter_rates, letter_rates, EMAIL_TYPE, datetime(2018, 1, 1))
+    rate = get_rate(non_letter_rates, [], EMAIL_TYPE, datetime(2018, 1, 1))
     assert rate == Decimal(0)
 
 

tests/app/db.py

@@ -1,6 +1,7 @@
 import random
 import uuid
 from datetime import datetime, date
+from decimal import Decimal
 
 from app import db
 from app.dao.email_branding_dao import dao_create_email_branding
@@ -29,6 +30,7 @@ from app.models import (
     Job,
     Notification,
     EmailBranding,
+    LetterRate,
     Organisation,
     Rate,
     Service,
@@ -403,6 +405,23 @@ def create_rate(start_date, value, notification_type):
     return rate
 
 
+def create_letter_rate(start_date=None, end_date=None, crown=True, sheet_count=1, rate=0.33, post_class='second'):
+    if start_date is None:
+        start_date = datetime(2016, 1, 1)
+    rate = LetterRate(
+        id=uuid.uuid4(),
+        start_date=start_date,
+        end_date=end_date,
+        crown=crown,
+        sheet_count=sheet_count,
+        rate=Decimal(rate),
+        post_class=post_class
+    )
+    db.session.add(rate)
+    db.session.commit()
+    return rate
+
+
 def create_api_key(service, key_type=KEY_TYPE_NORMAL):
     id_ = uuid.uuid4()
     api_key = ApiKey(