Hardcode quarter start to October

backdrop/core/timeseries.py

@@ -84,10 +84,25 @@ def start(self, timestamp):
     def valid_start_at(self, timestamp):
         return timestamp.day == 1
 
+
+class Quarter(Period):
+    def __init__(self):
+        self.name = "month"
+        self._delta = relativedelta(months=3)
+
+    def start(self, timestamp):
+        return timestamp.replace(month=10, day=1, hour=0, minute=0,
+                                 second=0, microsecond=0)
+
+    def valid_start_at(self, timestamp):
+        return False
+
+
 HOUR = Hour()
 DAY = Day()
 WEEK = Week()
 MONTH = Month()
+QUARTER = Quarter()
 PERIODS = [HOUR, DAY, WEEK, MONTH]
 
 

tests/core/test_timeseries.py

@@ -1,7 +1,7 @@
 from unittest import TestCase
 import datetime
 from hamcrest import assert_that, is_, contains
-from backdrop.core.timeseries import timeseries, WEEK, MONTH, DAY, HOUR
+from backdrop.core.timeseries import timeseries, WEEK, MONTH, DAY, HOUR, QUARTER
 from tests.support.test_helpers import d, d_tz
 
 
@@ -291,3 +291,11 @@ def test_that_a_range_of_five_hours_gives_us_five_data_points(self):
             (d_tz(2013, 4, 3, 15), d_tz(2013, 4, 3, 16)),
             (d_tz(2013, 4, 3, 16), d_tz(2013, 4, 3, 17))
         ))
+
+class TestQuarter(TestCase):
+    def test_that_returns_the_beginning_of_the_current_quarter(self):
+        some_datetime = d(2013, 12, 4, 10, 23, 43)
+
+        start = QUARTER.start(some_datetime)
+
+        assert_that(start, is_(d(2013, 10, 1, 0, 0, 0)))