docstr: Test the handle_missing string on 'none' and 'na_categorical'.
docstr_tok: ["Test","the","handle_missing","string","on","'none","'","and","'na_categorical","'","."]
code: def test_count_handle_missing_string(self):
      """Test the handle_missing string on 'none' and 'na_categorical'."""
      enc = encoders.CountEncoder(handle_missing="return_nan")
  
      enc.fit(X)
      out = enc.transform(X_t)
  
      self.assertIn("none", enc._handle_missing)
      self.assertTrue(pd.Series([6, 5, 3]).isin(out["none"]).all())
      self.assertTrue(out["none"].unique().shape == (4,))
      self.assertTrue(out["none"].isna().sum() == 3)
      self.assertTrue(
          pd.Series([6, 7, 3]).isin(out["na_categorical"]).all()
      )
      self.assertFalse(pd.Series([4]).isin(out["na_categorical"]).all())
      self.assertTrue(out["na_categorical"].unique().shape == (4,))
      self.assertTrue(out["na_categorical"].isna().sum() == 3)
  
file_path: category_encoders/tests/test_count.py
imports: import pandas
  from unittest import TestCase
  import numpy
  import category_encoders
label_desc: Use image node_id 2 for calling the TestCountEncoder obj's underlying member method code with example usage: obj.test_count_handle_missing_string() without return types