content: # -*- coding: utf-8 -*-
  
  import pandas as pd
  
  # Segregated collection of methods that require the BlockManager internal data
  # structure
  
  
  class TestSeriesBlockInternals(object):
  
      def test_setitem_invalidates_datetime_index_freq(self):
          # GH#24096 altering a datetime64tz Series inplace invalidates the
          #  `freq` attribute on the underlying DatetimeIndex
  
          dti = pd.date_range('20130101', periods=3, tz='US/Eastern')
          ts = dti[1]
          ser = pd.Series(dti)
          assert ser._values is not dti
          assert ser._values._data.base is not dti._data._data.base
          assert dti.freq == 'D'
          ser.iloc[1] = pd.NaT
          assert ser._values.freq is None
  
          # check that the DatetimeIndex was not altered in place
          assert ser._values is not dti
          assert ser._values._data.base is not dti._data._data.base
          assert dti[1] == ts
          assert dti.freq == 'D'
  
      def test_dt64tz_setitem_does_not_mutate_dti(self):
          # GH#21907, GH#24096
          dti = pd.date_range('2016-01-01', periods=10, tz='US/Pacific')
          ts = dti[0]
          ser = pd.Series(dti)
          assert ser._values is not dti
          assert ser._values._data.base is not dti._data._data.base
          assert ser._data.blocks[0].values is not dti
          assert (ser._data.blocks[0].values._data.base
                  is not dti._data._data.base)
  
          ser[::3] = pd.NaT
          assert ser[0] is pd.NaT
          assert dti[0] == ts
  