Hour validate if timestamp is at start of hour

backdrop/core/timeseries.py

@@ -34,9 +34,16 @@ def range(self, start, end):
 
 
 class Hour(Period):
+    def __init__(self):
+        self.name = "hour"
+        self._delta = timedelta(hours=1)
+
     def start(self, timestamp):
         return timestamp.replace(minute=0, second=0, microsecond=0)
 
+    def valid_start_at(self, timestamp):
+        return timestamp.time() == time(timestamp.hour, 0, 0, 0)
+
 
 class Day(Period):
     def __init__(self):

tests/core/test_timeseries.py

@@ -264,4 +264,20 @@ def test_that_returns_the_beginning_of_the_current_hour(self):
 
         assert_that(start, is_(d(2013, 10, 4, 10, 0, 0)))
 
+    def test_that_middle_of_the_hour_is_not_a_valid_start_at(self):
+        middle_of_the_hour = d(2013, 10, 18, 12, 31)
+
+        assert_that(HOUR.valid_start_at(middle_of_the_hour), is_(False))
+
+    def test_that_beginning_of_the_hour_is_a_valid_start_at(self):
+        beginning_of_the_hour = d(2013, 10, 18, 12, 0)
+
+        assert_that(HOUR.valid_start_at(beginning_of_the_hour), is_(True))
+
+    def test_that_returns_the_end_of_the_current_hour(self):
+        some_datetime = d(2013, 10, 4, 10, 23, 43)
+
+        end = HOUR.end(some_datetime)
+
+        assert_that(end, is_(d(2013, 10, 4, 11, 0, 0)))