code: from datetime import timedelta
  from operator import attrgetter
  from functools import partial
  
  import pytest
  import pytz
  import numpy as np
  
  import pandas as pd
  from pandas import offsets
  import pandas.util.testing as tm
  from pandas._libs.tslib import OutOfBoundsDatetime
  from pandas._libs.tslibs import conversion
  from pandas import (DatetimeIndex, Index, Timestamp, datetime, date_range,
                      to_datetime)
  
  
  class TestDatetimeIndex(object):
  
      def test_construction_caching(self):
  
          df = pd.DataFrame({'dt': pd.date_range('20130101', periods=3),
                             'dttz': pd.date_range('20130101', periods=3,
                                                   tz='US/Eastern'),
                             'dt_with_null': [pd.Timestamp('20130101'), pd.NaT,
                                              pd.Timestamp('20130103')],
                             'dtns': pd.date_range('20130101', periods=3,
                                                   freq='ns')})
          assert df.dttz.dtype.tz.zone == 'US/Eastern'
  
      @pytest.mark.parametrize('kwargs', [
          {'tz': 'dtype.tz'},
          {'dtype': 'dtype'},
          {'dtype': 'dtype', 'tz': 'dtype.tz'}])
      def test_construction_with_alt(self, kwargs, tz_aware_fixture):
          tz = tz_aware_fixture
          i = pd.date_range('20130101', periods=5, freq='H', tz=tz)
          kwargs = {key: attrgetter(val)(i) for key, val in kwargs.items()}
          result = DatetimeIndex(i, **kwargs)
          tm.assert_index_equal(i, result)
  
      @pytest.mark.parametrize('kwargs', [
          {'tz': 'dtype.tz'},
          {'dtype': 'dtype'},
          {'dtype': 'dtype', 'tz': 'dtype.tz'}])
      def test_construction_with_alt_tz_localize(self, kwargs, tz_aware_fixture):
          tz = tz_aware_fixture
          i = pd.date_range('20130101', periods=5, freq='H', tz=tz)
          kwargs = {key: attrgetter(val)(i) for key, val in kwargs.items()}
          result = DatetimeIndex(i.tz_localize(None).asi8, **kwargs)
          expected = i.tz_localize(None).tz_localize('UTC').tz_convert(tz)
          tm.assert_index_equal(result, expected)
  
          # localize into the provided tz
          i2 = DatetimeIndex(i.tz_localize(None).asi8, tz='UTC')
          expected = i.tz_localize(None).tz_localize('UTC')
          tm.assert_index_equal(i2, expected)
  
          # incompat tz/dtype
          pytest.raises(ValueError, lambda: DatetimeIndex(
              i.tz_localize(None).asi8, dtype=i.dtype, tz='US/Pacific'))
  
      def test_construction_index_with_mixed_timezones(self):
          # gh-11488: no tz results in DatetimeIndex
          result = Index([Timestamp('2011-01-01'),
                          Timestamp('2011-01-02')], name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01'),
                               Timestamp('2011-01-02')], name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is None
  
          # same tz results in DatetimeIndex
          result = Index([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                          Timestamp('2011-01-02 10:00', tz='Asia/Tokyo')],
                         name='idx')
          exp = DatetimeIndex(
              [Timestamp('2011-01-01 10:00'), Timestamp('2011-01-02 10:00')
               ], tz='Asia/Tokyo', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
          # same tz results in DatetimeIndex (DST)
          result = Index([Timestamp('2011-01-01 10:00', tz='US/Eastern'),
                          Timestamp('2011-08-01 10:00', tz='US/Eastern')],
                         name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 10:00'),
                               Timestamp('2011-08-01 10:00')],
                              tz='US/Eastern', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
          # Different tz results in Index(dtype=object)
          result = Index([Timestamp('2011-01-01 10:00'),
                          Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                         name='idx')
          exp = Index([Timestamp('2011-01-01 10:00'),
                       Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                      dtype='object', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert not isinstance(result, DatetimeIndex)
  
          result = Index([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                          Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                         name='idx')
          exp = Index([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                       Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                      dtype='object', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert not isinstance(result, DatetimeIndex)
  
          # length = 1
          result = Index([Timestamp('2011-01-01')], name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01')], name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is None
  
          # length = 1 with tz
          result = Index(
              [Timestamp('2011-01-01 10:00', tz='Asia/Tokyo')], name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 10:00')], tz='Asia/Tokyo',
                              name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
      def test_construction_index_with_mixed_timezones_with_NaT(self):
          # see gh-11488
          result = Index([pd.NaT, Timestamp('2011-01-01'),
                          pd.NaT, Timestamp('2011-01-02')], name='idx')
          exp = DatetimeIndex([pd.NaT, Timestamp('2011-01-01'),
                               pd.NaT, Timestamp('2011-01-02')], name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is None
  
          # Same tz results in DatetimeIndex
          result = Index([pd.NaT, Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                          pd.NaT, Timestamp('2011-01-02 10:00',
                                            tz='Asia/Tokyo')],
                         name='idx')
          exp = DatetimeIndex([pd.NaT, Timestamp('2011-01-01 10:00'),
                               pd.NaT, Timestamp('2011-01-02 10:00')],
                              tz='Asia/Tokyo', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
          # same tz results in DatetimeIndex (DST)
          result = Index([Timestamp('2011-01-01 10:00', tz='US/Eastern'),
                          pd.NaT,
                          Timestamp('2011-08-01 10:00', tz='US/Eastern')],
                         name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 10:00'), pd.NaT,
                               Timestamp('2011-08-01 10:00')],
                              tz='US/Eastern', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
          # different tz results in Index(dtype=object)
          result = Index([pd.NaT, Timestamp('2011-01-01 10:00'),
                          pd.NaT, Timestamp('2011-01-02 10:00',
                                            tz='US/Eastern')],
                         name='idx')
          exp = Index([pd.NaT, Timestamp('2011-01-01 10:00'),
                       pd.NaT, Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                      dtype='object', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert not isinstance(result, DatetimeIndex)
  
          result = Index([pd.NaT, Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                          pd.NaT, Timestamp('2011-01-02 10:00',
                                            tz='US/Eastern')], name='idx')
          exp = Index([pd.NaT, Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                       pd.NaT, Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                      dtype='object', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert not isinstance(result, DatetimeIndex)
  
          # all NaT
          result = Index([pd.NaT, pd.NaT], name='idx')
          exp = DatetimeIndex([pd.NaT, pd.NaT], name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is None
  
          # all NaT with tz
          result = Index([pd.NaT, pd.NaT], tz='Asia/Tokyo', name='idx')
          exp = DatetimeIndex([pd.NaT, pd.NaT], tz='Asia/Tokyo', name='idx')
  
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
          assert result.tz is not None
          assert result.tz == exp.tz
  
      def test_construction_dti_with_mixed_timezones(self):
          # GH 11488 (not changed, added explicit tests)
  
          # no tz results in DatetimeIndex
          result = DatetimeIndex(
              [Timestamp('2011-01-01'), Timestamp('2011-01-02')], name='idx')
          exp = DatetimeIndex(
              [Timestamp('2011-01-01'), Timestamp('2011-01-02')], name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
  
          # same tz results in DatetimeIndex
          result = DatetimeIndex([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                                  Timestamp('2011-01-02 10:00',
                                            tz='Asia/Tokyo')],
                                 name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 10:00'),
                               Timestamp('2011-01-02 10:00')],
                              tz='Asia/Tokyo', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
  
          # same tz results in DatetimeIndex (DST)
          result = DatetimeIndex([Timestamp('2011-01-01 10:00', tz='US/Eastern'),
                                  Timestamp('2011-08-01 10:00',
                                            tz='US/Eastern')],
                                 name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 10:00'),
                               Timestamp('2011-08-01 10:00')],
                              tz='US/Eastern', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
  
          # different tz coerces tz-naive to tz-awareIndex(dtype=object)
          result = DatetimeIndex([Timestamp('2011-01-01 10:00'),
                                  Timestamp('2011-01-02 10:00',
                                            tz='US/Eastern')], name='idx')
          exp = DatetimeIndex([Timestamp('2011-01-01 05:00'),
                               Timestamp('2011-01-02 10:00')],
                              tz='US/Eastern', name='idx')
          tm.assert_index_equal(result, exp, exact=True)
          assert isinstance(result, DatetimeIndex)
  
          # tz mismatch affecting to tz-aware raises TypeError/ValueError
  
          with pytest.raises(ValueError):
              DatetimeIndex([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                             Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                            name='idx')
  
          with tm.assert_raises_regex(TypeError,
                                      'data is already tz-aware'):
              DatetimeIndex([Timestamp('2011-01-01 10:00'),
                             Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                            tz='Asia/Tokyo', name='idx')
  
          with pytest.raises(ValueError):
              DatetimeIndex([Timestamp('2011-01-01 10:00', tz='Asia/Tokyo'),
                             Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                            tz='US/Eastern', name='idx')
  
          with tm.assert_raises_regex(TypeError,
                                      'data is already tz-aware'):
              # passing tz should results in DatetimeIndex, then mismatch raises
              # TypeError
              Index([pd.NaT, Timestamp('2011-01-01 10:00'),
                     pd.NaT, Timestamp('2011-01-02 10:00', tz='US/Eastern')],
                    tz='Asia/Tokyo', name='idx')
  
      def test_construction_base_constructor(self):
          arr = [pd.Timestamp('2011-01-01'), pd.NaT, pd.Timestamp('2011-01-03')]
          tm.assert_index_equal(pd.Index(arr), pd.DatetimeIndex(arr))
          tm.assert_index_equal(pd.Index(np.array(arr)),
                                pd.DatetimeIndex(np.array(arr)))
  
          arr = [np.nan, pd.NaT, pd.Timestamp('2011-01-03')]
          tm.assert_index_equal(pd.Index(arr), pd.DatetimeIndex(arr))
          tm.assert_index_equal(pd.Index(np.array(arr)),
                                pd.DatetimeIndex(np.array(arr)))
  
      def test_construction_outofbounds(self):
          # GH 13663
          dates = [datetime(3000, 1, 1), datetime(4000, 1, 1),
                   datetime(5000, 1, 1), datetime(6000, 1, 1)]
          exp = Index(dates, dtype=object)
          # coerces to object
          tm.assert_index_equal(Index(dates), exp)
  
          with pytest.raises(OutOfBoundsDatetime):
              # can't create DatetimeIndex
              DatetimeIndex(dates)
  
      def test_construction_with_ndarray(self):
          # GH 5152
          dates = [datetime(2013, 10, 7),
                   datetime(2013, 10, 8),
                   datetime(2013, 10, 9)]
          data = DatetimeIndex(dates, freq=pd.tseries.frequencies.BDay()).values
          result = DatetimeIndex(data, freq=pd.tseries.frequencies.BDay())
          expected = DatetimeIndex(['2013-10-07',
                                    '2013-10-08',
                                    '2013-10-09'],
                                   freq='B')
          tm.assert_index_equal(result, expected)
  
      def test_constructor_coverage(self):
          rng = date_range('1/1/2000', periods=10.5)
          exp = date_range('1/1/2000', periods=10)
          tm.assert_index_equal(rng, exp)
  
          msg = 'periods must be a number, got foo'
          with tm.assert_raises_regex(TypeError, msg):
              DatetimeIndex(start='1/1/2000', periods='foo', freq='D')
  
          pytest.raises(ValueError, DatetimeIndex, start='1/1/2000',
                        end='1/10/2000')
  
          pytest.raises(ValueError, DatetimeIndex, '1/1/2000')
  
          # generator expression
          gen = (datetime(2000, 1, 1) + timedelta(i) for i in range(10))
          result = DatetimeIndex(gen)
          expected = DatetimeIndex([datetime(2000, 1, 1) + timedelta(i)
                                    for i in range(10)])
          tm.assert_index_equal(result, expected)
  
          # NumPy string array
          strings = np.array(['2000-01-01', '2000-01-02', '2000-01-03'])
          result = DatetimeIndex(strings)
          expected = DatetimeIndex(strings.astype('O'))
          tm.assert_index_equal(result, expected)
  
          from_ints = DatetimeIndex(expected.asi8)
          tm.assert_index_equal(from_ints, expected)
  
          # string with NaT
          strings = np.array(['2000-01-01', '2000-01-02', 'NaT'])
          result = DatetimeIndex(strings)
          expected = DatetimeIndex(strings.astype('O'))
          tm.assert_index_equal(result, expected)
  
          from_ints = DatetimeIndex(expected.asi8)
          tm.assert_index_equal(from_ints, expected)
  
          # non-conforming
          pytest.raises(ValueError, DatetimeIndex,
                        ['2000-01-01', '2000-01-02', '2000-01-04'], freq='D')
  
          pytest.raises(ValueError, DatetimeIndex, start='2011-01-01',
                        freq='b')
          pytest.raises(ValueError, DatetimeIndex, end='2011-01-01',
                        freq='B')
          pytest.raises(ValueError, DatetimeIndex, periods=10, freq='D')
  
      @pytest.mark.parametrize('freq', ['AS', 'W-SUN'])
      def test_constructor_datetime64_tzformat(self, freq):
          # see GH#6572: ISO 8601 format results in pytz.FixedOffset
          idx = date_range('2013-01-01T00:00:00-05:00',
                           '2016-01-01T23:59:59-05:00', freq=freq)
          expected = date_range('2013-01-01T00:00:00', '2016-01-01T23:59:59',
                                freq=freq, tz=pytz.FixedOffset(-300))
          tm.assert_index_equal(idx, expected)
          # Unable to use `US/Eastern` because of DST
          expected_i8 = date_range('2013-01-01T00:00:00',
                                   '2016-01-01T23:59:59', freq=freq,
                                   tz='America/Lima')
          tm.assert_numpy_array_equal(idx.asi8, expected_i8.asi8)
  
          idx = date_range('2013-01-01T00:00:00+09:00',
                           '2016-01-01T23:59:59+09:00', freq=freq)
          expected = date_range('2013-01-01T00:00:00', '2016-01-01T23:59:59',
                                freq=freq, tz=pytz.FixedOffset(540))
          tm.assert_index_equal(idx, expected)
          expected_i8 = date_range('2013-01-01T00:00:00',
                                   '2016-01-01T23:59:59', freq=freq,
                                   tz='Asia/Tokyo')
          tm.assert_numpy_array_equal(idx.asi8, expected_i8.asi8)
  
          # Non ISO 8601 format results in dateutil.tz.tzoffset
          idx = date_range('2013/1/1 0:00:00-5:00', '2016/1/1 23:59:59-5:00',
                           freq=freq)
          expected = date_range('2013-01-01T00:00:00', '2016-01-01T23:59:59',
                                freq=freq, tz=pytz.FixedOffset(-300))
          tm.assert_index_equal(idx, expected)
          # Unable to use `US/Eastern` because of DST
          expected_i8 = date_range('2013-01-01T00:00:00',
                                   '2016-01-01T23:59:59', freq=freq,
                                   tz='America/Lima')
          tm.assert_numpy_array_equal(idx.asi8, expected_i8.asi8)
  
          idx = date_range('2013/1/1 0:00:00+9:00',
                           '2016/1/1 23:59:59+09:00', freq=freq)
          expected = date_range('2013-01-01T00:00:00', '2016-01-01T23:59:59',
                                freq=freq, tz=pytz.FixedOffset(540))
          tm.assert_index_equal(idx, expected)
          expected_i8 = date_range('2013-01-01T00:00:00',
                                   '2016-01-01T23:59:59', freq=freq,
                                   tz='Asia/Tokyo')
          tm.assert_numpy_array_equal(idx.asi8, expected_i8.asi8)
  
      def test_constructor_dtype(self):
  
          # passing a dtype with a tz should localize
          idx = DatetimeIndex(['2013-01-01', '2013-01-02'],
                              dtype='datetime64[ns, US/Eastern]')
          expected = DatetimeIndex(['2013-01-01', '2013-01-02']
                                   ).tz_localize('US/Eastern')
          tm.assert_index_equal(idx, expected)
  
          idx = DatetimeIndex(['2013-01-01', '2013-01-02'],
                              tz='US/Eastern')
          tm.assert_index_equal(idx, expected)
  
          # if we already have a tz and its not the same, then raise
          idx = DatetimeIndex(['2013-01-01', '2013-01-02'],
                              dtype='datetime64[ns, US/Eastern]')
  
          pytest.raises(ValueError,
                        lambda: DatetimeIndex(idx,
                                              dtype='datetime64[ns]'))
  
          # this is effectively trying to convert tz's
          pytest.raises(TypeError,
                        lambda: DatetimeIndex(idx,
                                              dtype='datetime64[ns, CET]'))
          pytest.raises(ValueError,
                        lambda: DatetimeIndex(
                            idx, tz='CET',
                            dtype='datetime64[ns, US/Eastern]'))
          result = DatetimeIndex(idx, dtype='datetime64[ns, US/Eastern]')
          tm.assert_index_equal(idx, result)
  
      def test_constructor_name(self):
          idx = DatetimeIndex(start='2000-01-01', periods=1, freq='A',
                              name='TEST')
          assert idx.name == 'TEST'
  
      def test_000constructor_resolution(self):
          # 2252
          t1 = Timestamp((1352934390 * 1000000000) + 1000000 + 1000 + 1)
          idx = DatetimeIndex([t1])
  
          assert idx.nanosecond[0] == t1.nanosecond
  
      def test_disallow_setting_tz(self):
          # GH 3746
          dti = DatetimeIndex(['2010'], tz='UTC')
          with pytest.raises(AttributeError):
              dti.tz = pytz.timezone('US/Pacific')
  
      @pytest.mark.parametrize('tz', [
          None, 'America/Los_Angeles', pytz.timezone('America/Los_Angeles'),
          Timestamp('2000', tz='America/Los_Angeles').tz])
      def test_constructor_start_end_with_tz(self, tz):
          # GH 18595
          start = Timestamp('2013-01-01 06:00:00', tz='America/Los_Angeles')
          end = Timestamp('2013-01-02 06:00:00', tz='America/Los_Angeles')
          result = DatetimeIndex(freq='D', start=start, end=end, tz=tz)
          expected = DatetimeIndex(['2013-01-01 06:00:00',
                                    '2013-01-02 06:00:00'],
                                   tz='America/Los_Angeles')
          tm.assert_index_equal(result, expected)
          # Especially assert that the timezone is consistent for pytz
          assert pytz.timezone('America/Los_Angeles') is result.tz
  
      @pytest.mark.parametrize('tz', ['US/Pacific', 'US/Eastern', 'Asia/Tokyo'])
      def test_constructor_with_non_normalized_pytz(self, tz):
          # GH 18595
          non_norm_tz = Timestamp('2010', tz=tz).tz
          result = DatetimeIndex(['2010'], tz=non_norm_tz)
          assert pytz.timezone(tz) is result.tz
  
      def test_constructor_timestamp_near_dst(self):
          # GH 20854
          ts = [Timestamp('2016-10-30 03:00:00+0300', tz='Europe/Helsinki'),
                Timestamp('2016-10-30 03:00:00+0200', tz='Europe/Helsinki')]
          result = DatetimeIndex(ts)
          expected = DatetimeIndex([ts[0].to_pydatetime(),
                                    ts[1].to_pydatetime()])
          tm.assert_index_equal(result, expected)
  
      @pytest.mark.parametrize('klass', [Index, DatetimeIndex])
      @pytest.mark.parametrize('box', [
          np.array, partial(np.array, dtype=object), list])
      @pytest.mark.parametrize('tz, dtype', [
          ['US/Pacific', 'datetime64[ns, US/Pacific]'],
          [None, 'datetime64[ns]']])
      def test_constructor_with_int_tz(self, klass, box, tz, dtype):
          # GH 20997, 20964
          ts = Timestamp('2018-01-01', tz=tz)
          result = klass(box([ts.value]), dtype=dtype)
          expected = klass([ts])
          assert result == expected
  
  
  class TestTimeSeries(object):
  
      def test_dti_constructor_preserve_dti_freq(self):
          rng = date_range('1/1/2000', '1/2/2000', freq='5min')
  
          rng2 = DatetimeIndex(rng)
          assert rng.freq == rng2.freq
  
      def test_dti_constructor_years_only(self, tz_naive_fixture):
          tz = tz_naive_fixture
          # GH 6961
          rng1 = date_range('2014', '2015', freq='M', tz=tz)
          expected1 = date_range('2014-01-31', '2014-12-31', freq='M', tz=tz)
  
          rng2 = date_range('2014', '2015', freq='MS', tz=tz)
          expected2 = date_range('2014-01-01', '2015-01-01', freq='MS', tz=tz)
  
          rng3 = date_range('2014', '2020', freq='A', tz=tz)
          expected3 = date_range('2014-12-31', '2019-12-31', freq='A', tz=tz)
  
          rng4 = date_range('2014', '2020', freq='AS', tz=tz)
          expected4 = date_range('2014-01-01', '2020-01-01', freq='AS', tz=tz)
  
          for rng, expected in [(rng1, expected1), (rng2, expected2),
                                (rng3, expected3), (rng4, expected4)]:
              tm.assert_index_equal(rng, expected)
  
      @pytest.mark.parametrize('dtype', [np.int64, np.int32, np.int16, np.int8])
      def test_dti_constructor_small_int(self, dtype):
          # GH 13721
          exp = DatetimeIndex(['1970-01-01 00:00:00.00000000',
                               '1970-01-01 00:00:00.00000001',
                               '1970-01-01 00:00:00.00000002'])
  
          arr = np.array([0, 10, 20], dtype=dtype)
          tm.assert_index_equal(DatetimeIndex(arr), exp)
  
      def test_ctor_str_intraday(self):
          rng = DatetimeIndex(['1-1-2000 00:00:01'])
          assert rng[0].second == 1
  
      def test_is_(self):
          dti = DatetimeIndex(start='1/1/2005', end='12/1/2005', freq='M')
          assert dti.is_(dti)
          assert dti.is_(dti.view())
          assert not dti.is_(dti.copy())
  
      def test_index_cast_datetime64_other_units(self):
          arr = np.arange(0, 100, 10, dtype=np.int64).view('M8[D]')
          idx = Index(arr)
  
          assert (idx.values == conversion.ensure_datetime64ns(arr)).all()
  
      def test_constructor_int64_nocopy(self):
          # GH#1624
          arr = np.arange(1000, dtype=np.int64)
          index = DatetimeIndex(arr)
  
          arr[50:100] = -1
          assert (index.asi8[50:100] == -1).all()
  
          arr = np.arange(1000, dtype=np.int64)
          index = DatetimeIndex(arr, copy=True)
  
          arr[50:100] = -1
          assert (index.asi8[50:100] != -1).all()
  
      @pytest.mark.parametrize('freq', ['M', 'Q', 'A', 'D', 'B', 'BH',
                                        'T', 'S', 'L', 'U', 'H', 'N', 'C'])
      def test_from_freq_recreate_from_data(self, freq):
          org = DatetimeIndex(start='2001/02/01 09:00', freq=freq, periods=1)
          idx = DatetimeIndex(org, freq=freq)
          tm.assert_index_equal(idx, org)
  
          org = DatetimeIndex(start='2001/02/01 09:00', freq=freq,
                              tz='US/Pacific', periods=1)
          idx = DatetimeIndex(org, freq=freq, tz='US/Pacific')
          tm.assert_index_equal(idx, org)
  
      def test_datetimeindex_constructor_misc(self):
          arr = ['1/1/2005', '1/2/2005', 'Jn 3, 2005', '2005-01-04']
          pytest.raises(Exception, DatetimeIndex, arr)
  
          arr = ['1/1/2005', '1/2/2005', '1/3/2005', '2005-01-04']
          idx1 = DatetimeIndex(arr)
  
          arr = [datetime(2005, 1, 1), '1/2/2005', '1/3/2005', '2005-01-04']
          idx2 = DatetimeIndex(arr)
  
          arr = [Timestamp(datetime(2005, 1, 1)), '1/2/2005', '1/3/2005',
                 '2005-01-04']
          idx3 = DatetimeIndex(arr)
  
          arr = np.array(['1/1/2005', '1/2/2005', '1/3/2005',
                          '2005-01-04'], dtype='O')
          idx4 = DatetimeIndex(arr)
  
          arr = to_datetime(['1/1/2005', '1/2/2005', '1/3/2005', '2005-01-04'])
          idx5 = DatetimeIndex(arr)
  
          arr = to_datetime(['1/1/2005', '1/2/2005', 'Jan 3, 2005', '2005-01-04'
                             ])
          idx6 = DatetimeIndex(arr)
  
          idx7 = DatetimeIndex(['12/05/2007', '25/01/2008'], dayfirst=True)
          idx8 = DatetimeIndex(['2007/05/12', '2008/01/25'], dayfirst=False,
                               yearfirst=True)
          tm.assert_index_equal(idx7, idx8)
  
          for other in [idx2, idx3, idx4, idx5, idx6]:
              assert (idx1.values == other.values).all()
  
          sdate = datetime(1999, 12, 25)
          edate = datetime(2000, 1, 1)
          idx = DatetimeIndex(start=sdate, freq='1B', periods=20)
          assert len(idx) == 20
          assert idx[0] == sdate + 0 * offsets.BDay()
          assert idx.freq == 'B'
  
          idx = DatetimeIndex(end=edate, freq=('D', 5), periods=20)
          assert len(idx) == 20
          assert idx[-1] == edate
          assert idx.freq == '5D'
  
          idx1 = DatetimeIndex(start=sdate, end=edate, freq='W-SUN')
          idx2 = DatetimeIndex(start=sdate, end=edate,
                               freq=offsets.Week(weekday=6))
          assert len(idx1) == len(idx2)
          assert idx1.freq == idx2.freq
  
          idx1 = DatetimeIndex(start=sdate, end=edate, freq='QS')
          idx2 = DatetimeIndex(start=sdate, end=edate,
                               freq=offsets.QuarterBegin(startingMonth=1))
          assert len(idx1) == len(idx2)
          assert idx1.freq == idx2.freq
  
          idx1 = DatetimeIndex(start=sdate, end=edate, freq='BQ')
          idx2 = DatetimeIndex(start=sdate, end=edate,
                               freq=offsets.BQuarterEnd(startingMonth=12))
          assert len(idx1) == len(idx2)
          assert idx1.freq == idx2.freq
  
apis: pandas.DatetimeIndex pandas.util.testing.assert_raises_regex pandas.date_range pandas.util.testing.assert_numpy_array_equal pandas.offsets.Week pandas.offsets.QuarterBegin pandas.datetime pandas.offsets.BQuarterEnd pandas.offsets.BDay numpy.arange pandas.to_datetime pandas.util.testing.assert_index_equal pandas.tseries.frequencies.BDay pandas._libs.tslibs.conversion.ensure_datetime64ns numpy.array pandas.Index pandas.Timestamp