code: def test_search(self):
      expected = pd.DataFrame(
          {
              "text": [
                  "What art thou that usurp'st this time of night,",
                  "Together with that fair and warlike form",
              ],
              "category": ["hamlet", "hamlet"],
              "index": [0, 1],
          }
      )
      self.assertIsInstance(self.corpus, CorpusDF)
      returned = self.corpus.search("that")
      pd.testing.assert_frame_equal(
          expected, returned[expected.columns]
      )
  
file_path: scattertext/scattertext/test/test_corpusFromPandas.py
imports: from unittest import TestCase
  import numpy
  import pandas
  from scattertext import chinese_nlp, CorpusDF
  from scattertext import whitespace_nlp
  from scattertext.CorpusFromPandas import CorpusFromPandas
label_desc: Use image node_id 4 for calling the TestCorpusFromPandas obj's underlying member method code with example usage: obj.test_search() without return types