code: def test_valid(self, datetime_series):
      ts = datetime_series.copy()
      ts.index = ts.index._with_freq(None)
      ts[::2] = np.nan
  
      result = ts.dropna()
      assert len(result) == ts.count()
      tm.assert_series_equal(result, ts[1::2])
      tm.assert_series_equal(result, ts[pd.notna(ts)])
  
file_path: pandas/pandas/tests/series/test_missing.py
imports: from datetime import timedelta
  import numpy
  import pytest
  from pandas._libs import iNaT
  import pandas
  from pandas import Categorical, Index, NaT, Series, isna
  import pandas._testing
label_desc: Use image node_id 5 for calling the TestSeriesMissingData obj's underlying member method code with example usage: obj.test_valid(datetime_series) without return types