code: def test_astype_raises(self, dtype):
      # GH 13149, GH 13209
      idx = DatetimeIndex(["2016-05-16", "NaT", NaT, np.nan])
      msg = "Cannot cast DatetimeIndex to dtype"
      if dtype == "datetime64":
          msg = (
              "Casting to unit-less dtype 'datetime64' is not supported"
          )
      with pytest.raises(TypeError, match=msg):
          idx.astype(dtype)
  
imports: from datetime import datetime
  import dateutil
  import numpy
  import pytest
  import pytz
  import pandas
  from pandas import DatetimeIndex, Index, NaT, PeriodIndex, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 17 for calling the TestDatetimeIndex obj's underlying member method code with example usage: obj.test_astype_raises(dtype) without return types