code: def test_category_outputs_correct_results():
      df = pd.DataFrame(
          {"col1": ["a", "b", "c"], "col2": [1.0, 2.0, 3.0]}
      )
      res = MatchCategories(
          variables=["col1", "col2"], ignore_format=True
      ).fit_transform(df)
      pd.testing.assert_frame_equal(
          df, res, check_dtype=False, check_categorical=False
      )
  
      df = pd.DataFrame(
          {"col1": ["a", "b", None], "col2": [1.0, 2.0, np.nan]}
      )
      res = MatchCategories(
          variables=["col1", "col2"],
          ignore_format=True,
          missing_values="ignore",
      ).fit_transform(df)
      pd.testing.assert_frame_equal(
          df, res, check_dtype=False, check_categorical=False
      )
  
imports: import warnings
  import numpy
  import pandas
  import pytest
  from feature_engine.preprocessing import MatchCategories
label_desc: Use image node_id 3 for calling a global function with example usage: test_category_outputs_correct_results() without return types