code: def test_null_rows(dataframe):
      dataframe = dataframe.copy()
      dataframe.loc[1] = None
      dataframe.loc[4] = None
      dataframe.loc[6] = None
  
      df = dataframe.data_description.df
      assert (df["count"] == 6).all()
      assert np.isclose(df["pct_missing"], (3 / 9)).all()
  
file_path: pyjanitor/tests/functions/test_data_description.py
imports: import numpy
  import pytest
label_desc: Use image node_id 5 for calling a global function with example usage: test_null_rows(dataframe) without return types