Add date helper methods to be used as date range filters for notification counts

app/utils.py

@@ -1,3 +1,5 @@
+from datetime import datetime, timedelta
+
 from flask import url_for
 from app.models import SMS_TYPE, EMAIL_TYPE
 from notifications_utils.template import SMSMessageTemplate, PlainTextEmailTemplate
@@ -26,3 +28,13 @@ def get_template_instance(template, values):
     return {
         SMS_TYPE: SMSMessageTemplate, EMAIL_TYPE: PlainTextEmailTemplate
     }[template['template_type']](template, values)
+
+
+def get_midnight_for_date(date):
+    midnight = datetime.combine(date, datetime.min.time())
+    return midnight
+
+
+def get_midnight_for_day_before(date):
+    day_before = date - timedelta(1)
+    return get_midnight_for_date(day_before)

tests/app/test_utils.py

@@ -0,0 +1,25 @@
+from datetime import datetime
+import pytest
+
+from app.utils import (
+    get_midnight_for_date,
+    get_midnight_for_day_before
+)
+
+
+@pytest.mark.parametrize('date, expected_date', [
+    (datetime(2016, 1, 15, 0, 30), datetime(2016, 1, 15, 0, 0)),
+    (datetime(2016, 1, 15, 0, 0), datetime(2016, 1, 15, 0, 0)),
+    (datetime(2016, 1, 15, 11, 59), datetime(2016, 1, 15, 0, 0)),
+])
+def test_get_midnight_for_today_returns_expected_date(date, expected_date):
+    assert get_midnight_for_date(date) == expected_date
+
+
+@pytest.mark.parametrize('date, expected_date', [
+    (datetime(2016, 1, 15, 0, 30), datetime(2016, 1, 14, 0, 0)),
+    (datetime(2016, 1, 15, 0, 0), datetime(2016, 1, 14, 0, 0)),
+    (datetime(2016, 1, 15, 11, 59), datetime(2016, 1, 14, 0, 0)),
+])
+def test_get_midnight_for_day_before_returns_expected_date(date, expected_date):
+    assert get_midnight_for_day_before(date) == expected_date