Merge pull request #763 from cssherry/partial_minutes_582

Closes #582: Allow partial minutes for python 3.6 or newer

changelog.d/582.bug.rst

@@ -0,0 +1 @@
+Added support for sub-minute offsets in Python 3.6+. Fixed by @cssherry (gh issue #582, pr #763)

dateutil/test/test_tz.py

@@ -156,6 +156,8 @@
 EST_TUPLE = ('EST', timedelta(hours=-5), timedelta(hours=0))
 EDT_TUPLE = ('EDT', timedelta(hours=-4), timedelta(hours=1))
 
+SUPPORTS_SUB_MINUTE_OFFSETS = sys.version_info >= (3, 6)
+
 
 ###
 # Helper functions
@@ -760,6 +762,25 @@ def test_tzoffset_singleton(args):
 
     assert tz1 is tz2
 
+
+@pytest.mark.tzoffset
+@pytest.mark.skipif(not SUPPORTS_SUB_MINUTE_OFFSETS,
+                    reason='Sub-minute offsets not supported')
+def test_tzoffset_sub_minute():
+    delta = timedelta(hours=12, seconds=30)
+    test_datetime = datetime(2000, 1, 1, tzinfo=tz.tzoffset(None, delta))
+    assert test_datetime.utcoffset() == delta
+
+
+@pytest.mark.tzoffset
+@pytest.mark.skipif(SUPPORTS_SUB_MINUTE_OFFSETS,
+                    reason='Sub-minute offsets supported')
+def test_tzoffset_sub_minute_rounding():
+    delta = timedelta(hours=12, seconds=30)
+    test_date = datetime(2000, 1, 1, tzinfo=tz.tzoffset(None, delta))
+    assert test_date.utcoffset() == timedelta(hours=12, minutes=1)
+
+
 @pytest.mark.tzlocal
 class TzLocalTest(unittest.TestCase):
     def testEquality(self):
@@ -1908,11 +1929,10 @@ def testFilestreamWithNameRepr(self):
         tzc = tz.tzfile(fileobj)
         self.assertEqual(repr(tzc), 'tzfile(' + repr('foo') + ')')
 
-    def testRoundNonFullMinutes(self):
-        # This timezone has an offset of 5992 seconds in 1900-01-01.
-        tzc = tz.tzfile(BytesIO(base64.b64decode(EUROPE_HELSINKI)))
-        self.assertEqual(str(datetime(1900, 1, 1, 0, 0, tzinfo=tzc)),
-                             "1900-01-01 00:00:00+01:40")
+
+
+
+
 
     def testLeapCountDecodesProperly(self):
         # This timezone has leapcnt, and failed to decode until
@@ -1974,6 +1994,27 @@ def testTZSetDoesntCorrupt(self):
             self.assertEqual(str(dt), '2014-07-20 12:34:56+00:00')
 
 
+@pytest.mark.tzfile
+@pytest.mark.skipif(not SUPPORTS_SUB_MINUTE_OFFSETS,
+                    reason='Sub-minute offsets not supported')
+def test_tzfile_sub_minute_offset():
+    # If user running python 3.6 or newer, exact offset is used
+    tzc = tz.tzfile(BytesIO(base64.b64decode(EUROPE_HELSINKI)))
+    offset = timedelta(hours=1, minutes=39, seconds=52)
+    assert datetime(1900, 1, 1, 0, 0, tzinfo=tzc).utcoffset() == offset
+
+
+@pytest.mark.tzfile
+@pytest.mark.skipif(SUPPORTS_SUB_MINUTE_OFFSETS,
+                    reason='Sub-minute offsets supported.')
+def test_sub_minute_rounding_tzfile():
+    # This timezone has an offset of 5992 seconds in 1900-01-01.
+    # For python version pre-3.6, this will be rounded
+    tzc = tz.tzfile(BytesIO(base64.b64decode(EUROPE_HELSINKI)))
+    offset = timedelta(hours=1, minutes=40)
+    assert datetime(1900, 1, 1, 0, 0, tzinfo=tzc).utcoffset() == offset
+
+
 @unittest.skipUnless(IS_WIN, "Requires Windows")
 class TzWinTest(unittest.TestCase, TzWinFoldMixin):
     def setUp(self):
@@ -2618,33 +2659,28 @@ def __get_kiritimati_resolve_imaginary_test():
     return (tzi, ) + dates
 
 
-@pytest.mark.tz_resolve_imaginary
-@pytest.mark.parametrize('tzi, dt, dt_exp', [
+resolve_imaginary_tests = [
     (tz.gettz('Europe/London'),
      datetime(2018, 3, 25, 1, 30), datetime(2018, 3, 25, 2, 30)),
     (tz.gettz('America/New_York'),
      datetime(2017, 3, 12, 2, 30), datetime(2017, 3, 12, 3, 30)),
     (tz.gettz('Australia/Sydney'),
      datetime(2014, 10, 5, 2, 0), datetime(2014, 10, 5, 3, 0)),
     __get_kiritimati_resolve_imaginary_test(),
-])
-def test_resolve_imaginary(tzi, dt, dt_exp):
-    dt = dt.replace(tzinfo=tzi)
-    dt_exp = dt_exp.replace(tzinfo=tzi)
+]
 
-    dt_r = tz.resolve_imaginary(dt)
-    assert dt_r == dt_exp
-    assert dt_r.tzname() == dt_exp.tzname()
-    assert dt_r.utcoffset() == dt_exp.utcoffset()
+
+if SUPPORTS_SUB_MINUTE_OFFSETS:
+    resolve_imaginary_tests.append(
+        (tz.gettz('Africa/Monrovia'),
+         datetime(1972, 1, 7, 0, 30), datetime(1972, 1, 7, 1, 14, 30)))
 
 
-@pytest.mark.xfail
 @pytest.mark.tz_resolve_imaginary
-def test_resolve_imaginary_monrovia():
-    # See GH #582 - When that is resolved, move this into test_resolve_imaginary
-    tzi = tz.gettz('Africa/Monrovia')
-    dt = datetime(1972, 1, 7, hour=0, minute=30, second=0, tzinfo=tzi)
-    dt_exp = datetime(1972, 1, 7, hour=1, minute=14, second=30, tzinfo=tzi)
+@pytest.mark.parametrize('tzi, dt, dt_exp', resolve_imaginary_tests)
+def test_resolve_imaginary(tzi, dt, dt_exp):
+    dt = dt.replace(tzinfo=tzi)
+    dt_exp = dt_exp.replace(tzinfo=tzi)
 
     dt_r = tz.resolve_imaginary(dt)
     assert dt_r == dt_exp

dateutil/tz/tz.py

@@ -29,6 +29,9 @@
 except ImportError:
     tzwin = tzwinlocal = None
 
+# For warning about rounding tzinfo
+from warnings import warn
+
 ZERO = datetime.timedelta(0)
 EPOCH = datetime.datetime.utcfromtimestamp(0)
 EPOCHORDINAL = EPOCH.toordinal()
@@ -138,7 +141,8 @@ def __init__(self, name, offset):
             offset = offset.total_seconds()
         except (TypeError, AttributeError):
             pass
-        self._offset = datetime.timedelta(seconds=offset)
+
+        self._offset = datetime.timedelta(seconds=_get_supported_offset(offset))
 
     def utcoffset(self, dt):
         return self._offset
@@ -601,10 +605,7 @@ def _read_tzfile(self, fileobj):
         out.ttinfo_list = []
         for i in range(typecnt):
             gmtoff, isdst, abbrind = ttinfo[i]
-            # Round to full-minutes if that's not the case. Python's
-            # datetime doesn't accept sub-minute timezones. Check
-            # http://python.org/sf/1447945 for some information.
-            gmtoff = 60 * ((gmtoff + 30) // 60)
+            gmtoff = _get_supported_offset(gmtoff)
             tti = _ttinfo()
             tti.offset = gmtoff
             tti.dstoffset = datetime.timedelta(0)
@@ -1769,6 +1770,20 @@ def _datetime_to_timestamp(dt):
     return (dt.replace(tzinfo=None) - EPOCH).total_seconds()
 
 
+if sys.version_info >= (3, 6):
+    def _get_supported_offset(second_offset):
+        return second_offset
+else:
+    def _get_supported_offset(second_offset):
+        # For python pre-3.6, round to full-minutes if that's not the case.
+        # Python's datetime doesn't accept sub-minute timezones. Check
+        # http://python.org/sf/1447945 or https://bugs.python.org/issue5288
+        # for some information.
+        old_offset = second_offset
+        calculated_offset = 60 * ((second_offset + 30) // 60)
+        return calculated_offset
+
+
 class _ContextWrapper(object):
     """
     Class for wrapping contexts so that they are passed through in a