TST: remove DST transition scenarios from test_dti_tz_localize_roundt…

…rip pandas-dev#24689

pandas/tests/indexes/datetimes/test_timezones.py

@@ -6,7 +6,7 @@
 from distutils.version import LooseVersion
 
 import dateutil
-from dateutil.tz import gettz, tzlocal
+from dateutil.tz import gettz, tzlocal, tzutc
 import numpy as np
 import pytest
 import pytz
@@ -434,24 +434,30 @@ def test_dti_tz_localize_utc_conversion(self, tz):
         with pytest.raises(pytz.NonExistentTimeError):
             rng.tz_localize(tz)
 
+    @pytest.mark.parametrize('tz', [
+        'UTC', 'US/Eastern', 'Europe/London', 'Asia/Tokyo', 'Australia/NSW',
+        'dateutil/US/Pacific', 'dateutil/Asia/Singapore', tzutc(),
+        pytz.FixedOffset(300), pytz.FixedOffset(0), pytz.FixedOffset(-300)
+    ])
     @pytest.mark.parametrize('idx', [
-        date_range(start='2014-01-01', end='2014-12-31', freq='M'),
-        date_range(start='2014-01-01', end='2014-12-31', freq='D'),
-        date_range(start='2014-01-01', end='2014-03-01', freq='H'),
-        date_range(start='2014-08-01', end='2014-10-31', freq='T')
+        date_range(start='2014-12-01', end='2015-02-28', freq='D'),
+        date_range(start='2014-05-01', end='2015-07-31', freq='D'),
+        date_range(start='2014-01-01', end='2014-02-28', freq='H'),
+        date_range(start='2014-08-01', end='2014-09-30', freq='15T')
     ])
-    def test_dti_tz_localize_roundtrip(self, tz_aware_fixture, idx):
-        tz = tz_aware_fixture
+    def test_dti_tz_localize_roundtrip(self, tz, idx):
+        # note: this tz tests that a tz-naive index can be localized
+        # and de-localized successfully, when there are no DST transitions
+        # in the range.
         localized = idx.tz_localize(tz)
-        expected = date_range(start=idx[0], end=idx[-1], freq=idx.freq,
-                              tz=tz)
-        tm.assert_index_equal(localized, expected)
+
+        # cant localize a tz-aware object
         with pytest.raises(TypeError):
             localized.tz_localize(tz)
 
         reset = localized.tz_localize(None)
-        tm.assert_index_equal(reset, idx)
         assert reset.tzinfo is None
+        tm.assert_index_equal(reset, idx)
 
     def test_dti_tz_localize_naive(self):
         rng = date_range('1/1/2011', periods=100, freq='H')