TST: Add unit tests for older timezone issues

doc/source/whatsnew/v0.23.2.txt

@@ -79,6 +79,11 @@ Bug Fixes
 **Timezones**
 - Bug in :class:`Timestamp` and :class:`DatetimeIndex` where passing a :class:`Timestamp` localized after a DST transition would return a datetime before the DST transition (:issue:`20854`)
 - Bug in comparing :class:`DataFrame`s with tz-aware :class:`DatetimeIndex` columns with a DST transition that raised a ``KeyError`` (:issue:`19970`)
+- Bug in :meth:`DatetimeIndex.shift` where an ``AssertionError`` would raise when shifting across DST (:issue:`8616`)
+- Bug in :class:`Timestamp` constructor where passing an invalid timezone offset designator (``Z``) would not raise a ``ValueError``(:issue:`8910`)
+- Bug in :meth:`Timestamp.replace` where replacing at a DST boundary would retain an incorrect offset (:issue:`7825`)
+- Bug in :meth:`DatetimeIndex.reindex` when reindexing a tz-naive and tz-aware :class:`DatetimeIndex` (:issue:`8306`)
+- Bug in :meth:`DatetimeIndex.resample` when downsampling across a DST boundary (:issue:`8531`)
 
 **Other**
 

pandas/tests/indexes/datetimes/test_arithmetic.py

@@ -4,7 +4,7 @@
 import operator
 
 import pytest
-
+import pytz
 import numpy as np
 
 import pandas as pd
@@ -476,6 +476,28 @@ def test_dti_shift_localized(self, tzstr):
         result = dr_tz.shift(1, '10T')
         assert result.tz == dr_tz.tz
 
+    def test_dti_shift_across_dst(self):
+        # GH 8616
+        idx = date_range('2013-11-03', tz='America/Chicago',
+                         periods=7, freq='H')
+        s = Series(index=idx[:-1])
+        result = s.shift(freq='H')
+        expected = Series(index=idx[1:])
+        tm.assert_series_equal(result, expected)
+
+    @pytest.mark.parametrize('shift, result_time', [
+        [0, '2014-11-14 00:00:00'],
+        [-1, '2014-11-13 23:00:00'],
+        [1, '2014-11-14 01:00:00']])
+    def test_dti_shift_near_midnight(self, shift, result_time):
+        # GH 8616
+        dt = datetime(2014, 11, 14, 0)
+        dt_est = pytz.timezone('EST').localize(dt)
+        s = Series(data=[1], index=[dt_est])
+        result = s.shift(shift, freq='H')
+        expected = Series(1, index=DatetimeIndex([result_time], tz='EST'))
+        tm.assert_series_equal(result, expected)
+
     # -------------------------------------------------------------
     # Binary operations DatetimeIndex and timedelta-like
 

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -420,6 +420,12 @@ def test_constructor_nanosecond(self, result):
         expected = expected + Timedelta(nanoseconds=1)
         assert result == expected
 
+    @pytest.mark.parametrize('z', ['Z0', 'Z00'])
+    def test_constructor_invalid_Z0_isostring(self, z):
+        # GH 8910
+        with pytest.raises(ValueError):
+            Timestamp('2014-11-02 01:00{}'.format(z))
+
     @pytest.mark.parametrize('arg', ['year', 'month', 'day', 'hour', 'minute',
                                      'second', 'microsecond', 'nanosecond'])
     def test_invalid_date_kwarg_with_string_input(self, arg):

pandas/tests/scalar/timestamp/test_unary_ops.py

@@ -238,6 +238,13 @@ def test_replace_across_dst(self, tz, normalize):
         ts2b = normalize(ts2)
         assert ts2 == ts2b
 
+    def test_replace_dst_border(self):
+        # Gh 7825
+        t = Timestamp('2013-11-3', tz='America/Chicago')
+        result = t.replace(hour=3)
+        expected = Timestamp('2013-11-3 03:00:00', tz='America/Chicago')
+        assert result == expected
+
     # --------------------------------------------------------------
 
     @td.skip_if_windows

pandas/tests/series/indexing/test_alter_index.py

@@ -453,6 +453,15 @@ def test_reindex_fill_value():
     assert_series_equal(result, expected)
 
 
+def test_reindex_datetimeindexes_tz_naive_and_aware():
+    # GH 8306
+    idx = date_range('20131101', tz='America/Chicago', periods=7)
+    newidx = date_range('20131103', periods=10, freq='H')
+    s = Series(range(7), index=idx)
+    with pytest.raises(TypeError):
+        s.reindex(newidx, method='ffill')
+
+
 def test_rename():
     # GH 17407
     s = Series(range(1, 6), index=pd.Index(range(2, 7), name='IntIndex'))

pandas/tests/test_resample.py

@@ -2084,6 +2084,17 @@ def test_resample_dst_anchor(self):
                                        freq='D', tz='Europe/Paris')),
             'D Frequency')
 
+    def test_downsample_across_dst(self):
+        # GH 8531
+        tz = pytz.timezone('Europe/Berlin')
+        dt = datetime(2014, 10, 26)
+        dates = date_range(tz.localize(dt), periods=4, freq='2H')
+        result = Series(5, index=dates).resample('H').mean()
+        expected = Series([5., np.nan] * 3 + [5.],
+                          index=date_range(tz.localize(dt), periods=7,
+                                           freq='H'))
+        tm.assert_series_equal(result, expected)
+
     def test_resample_with_nat(self):
         # GH 13020
         index = DatetimeIndex([pd.NaT,