code: def test_values(self):
      idx = PeriodIndex([], freq="M")
  
      exp = np.array([], dtype=object)
      tm.assert_numpy_array_equal(idx.values, exp)
      tm.assert_numpy_array_equal(idx.to_numpy(), exp)
  
      exp = np.array([], dtype=np.int64)
      tm.assert_numpy_array_equal(idx.asi8, exp)
  
      idx = PeriodIndex(["2011-01", NaT], freq="M")
  
      exp = np.array([Period("2011-01", freq="M"), NaT], dtype=object)
      tm.assert_numpy_array_equal(idx.values, exp)
      tm.assert_numpy_array_equal(idx.to_numpy(), exp)
      exp = np.array([492, -9223372036854775808], dtype=np.int64)
      tm.assert_numpy_array_equal(idx.asi8, exp)
  
      idx = PeriodIndex(["2011-01-01", NaT], freq="D")
  
      exp = np.array(
          [Period("2011-01-01", freq="D"), NaT], dtype=object
      )
      tm.assert_numpy_array_equal(idx.values, exp)
      tm.assert_numpy_array_equal(idx.to_numpy(), exp)
      exp = np.array([14975, -9223372036854775808], dtype=np.int64)
      tm.assert_numpy_array_equal(idx.asi8, exp)
  
file_path: pandas/pandas/tests/indexes/period/test_period.py
imports: import numpy
  import pytest
  from pandas import Index, NaT, Period, PeriodIndex, Series, date_range, offsets, period_range
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestPeriodIndex obj's underlying member method code with example usage: obj.test_values() without return types