code: def test_astype_raises(self, dtype):
      # GH#13149, GH#13209
      idx = PeriodIndex(["2016-05-16", "NaT", NaT, np.nan], freq="D")
      msg = "Cannot cast PeriodIndex to dtype"
      with pytest.raises(TypeError, match=msg):
          idx.astype(dtype)
  
file_path: pandas/pandas/tests/indexes/period/methods/test_astype.py
imports: import numpy
  import pytest
  from pandas import CategoricalIndex, DatetimeIndex, Index, NaT, Period, PeriodIndex, period_range
  import pandas._testing
label_desc: Use image node_id 1 for calling the TestPeriodIndexAsType obj's underlying member method code with example usage: obj.test_astype_raises(dtype) without return types