docstr: Check if correct value is returned for filling in case of different
  column type and fill method
docstr_tok: ["Check","if","correct","value","is","returned","for","filling","in","case","of","different","column","type","and","fill","method"]
code: def test_get_fill_value(self):
      """
      Check if correct value is returned for filling in case of different
      column type and fill method
      """
      d = {
          "col1": [1, 2, 3, np.nan, np.nan],
          "col2": ["a", "a", np.nan, "b", "c"],
      }
      df = pd.DataFrame(data=d)
      # fill with median
      preprocess_missing = PreprocessingMissingValues(
          df.columns, PreprocessingMissingValues.FILL_NA_MEDIAN
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col1"]), 2
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col2"]), "a"
      )
      # fill with mean
      preprocess_missing = PreprocessingMissingValues(
          df.columns, PreprocessingMissingValues.FILL_NA_MEDIAN
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col1"]), 2
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col2"]), "a"
      )
      # fill with min
      preprocess_missing = PreprocessingMissingValues(
          df.columns, PreprocessingMissingValues.FILL_NA_MIN
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col1"]), 0
      )
      self.assertEqual(
          preprocess_missing._get_fill_value(df["col2"]),
          "_missing_value_",
      )
  
file_path: mljar-supervised/tests/tests_preprocessing/test_preprocessing_missing.py
imports: import unittest
  import tempfile
  import numpy
  import pandas
  from supervised.preprocessing.preprocessing_utils import PreprocessingUtils
  from supervised.preprocessing.preprocessing_missing import PreprocessingMissingValues
label_desc: Use image node_id 2 for calling the PreprocessingMissingValuesTest obj's underlying member method code with example usage: obj.test_get_fill_value() without return types