code: def test_astype_different_datetime_resos(using_copy_on_write):
      df = DataFrame(
          {"a": date_range("2019-12-31", periods=2, freq="D")}
      )
      result = df.astype("datetime64[ms]")
  
      assert not np.shares_memory(
          get_array(df, "a"), get_array(result, "a")
      )
      if using_copy_on_write:
          assert result._mgr._has_no_reference(0)
  
imports: import pickle
  import numpy
  import pytest
  from pandas.compat.pyarrow import pa_version_under12p0
  import pandas
  from pandas import DataFrame, Series, Timestamp, date_range
  import pandas._testing
  from pandas.tests.copy_view.util import get_array
label_desc: Use image node_id 9 for calling a global function with example usage: test_astype_different_datetime_resos(using_copy_on_write) without return types