Merge lp:~rockstar/entertainer/fix-weather-tests-again into lp:entertainer

[Paul Hummer]

The weather tests are no longer fragile to what time of day it is, or what timezone it is.

[Paul Hummer (rockstar)]

This branch looks a lot more heavy than it really is. For us that don't live in England, there are windows of time where one of the weather tests doesn't pass. This is because my datetime.now() is a different day than what day Google knows it is in Bath, England.

Initially, I thought datetime.utcnow() would be fine, since UTC 0 is England, but that still doesn't work, because utcnow() doesn't compensate for DST. The solution in this branch implements a tzinfo object specific to England, which I could then pass to datetime.now to specify a timezone which understands DST.

This will make the tests pass no matter what time it is in your local timezone, and no matter whether or not it's DST.

[Matt Layman (mblayman)]

Conceptually, I understand what you're doing. I'll confess I don't understand all the actual code, but I'll assume that you took the time to do proper research into subclassing tzinfo. The proof is in the pudding: the test passes now (I'm currently in a time of day where it would fail).

review: Approve

=== modified file 'entertainerlib/tests/test_weather.py'
--- entertainerlib/tests/test_weather.py	2009-02-10 00:59:03 +0000
+++ entertainerlib/tests/test_weather.py	2009-05-06 01:59:02 +0000
@@ -4,7 +4,7 @@
 __copyright__ = "2008, Jamie Bennett"
 __author__ = "Jamie Bennett <[e-mail]>"
 
-from datetime import datetime
+from datetime import datetime, timedelta, tzinfo
 
 from entertainerlib.tests import EntertainerTest
 from entertainerlib.utils.weather import Weather
@@ -27,11 +27,62 @@
 
     def testWeatherFindRemote(self):
         """Tests the weather code using a call to the outside world"""
+        class EnglandTimeZone(tzinfo):
+            '''An implementation of tzinfo specific to England.'''
+            def __init__(self):
+                tzinfo.__init__(self)
+                self.stdoffset = timedelta(hours=0)
+                self.reprname = 'England'
+                self.stdname = 'WET' # Western Europe Time
+                self.dstname = 'BST' # British Summer Time
+
+            def __repr__(self):
+                return self.reprname
+
+            def _first_sunday_on_or_after(self, dt):
+                '''Figure out the DST date.'''
+                days_to_go = 6 - dt.weekday()
+                if days_to_go:
+                    dt += timedelta(days_to_go)
+                return dt
+
+            def tzname(self, dt):
+                '''See `tzinfo.tzname`.'''
+                if self.dst(dt):
+                    return self.dstname
+                else:
+                    return self.stdname
+
+            def utcoffset(self, dt):
+                '''See `tzinfo.utcoffset`.'''
+                return self.stdoffset + self.dst(dt)
+
+            def dst(self, dt):
+                '''See `tzinfo.dst`.'''
+                DSTSTART = datetime(1, 4, 1, 2)
+                DSTEND = datetime(1, 10, 25, 1)
+                ZERO = timedelta(0)
+                HOUR = timedelta(hours=1)
+                if dt is None or dt.tzinfo is None:
+                    return ZERO
+                assert dt.tzinfo is self
+
+                start = self._first_sunday_on_or_after(
+                    DSTSTART.replace(year=dt.year))
+                end = self._first_sunday_on_or_after(
+                    DSTEND.replace(year=dt.year))
+
+                if start <= dt.replace(tzinfo=None) < end:
+                    return HOUR
+                else:
+                    return ZERO
+        england = EnglandTimeZone()
+
         self.weather.set_location('Bath,England')
         self.weather.refresh()
         forecasts = self.weather.get_forecasts()
         today = forecasts[0]
-        day = datetime.now().strftime('%a')
+        day = datetime.now(england).strftime('%a')
         self.assertEqual(str(today["Day"]), day)
 
     def testWeatherSet(self):