def test_set_prefix_pad(self):
     tok = QgramTokenizer()
     self.assertEqual(tok.get_prefix_pad(), '#')
     self.assertEqual(
         tok.tokenize('database'),
         ['#d', 'da', 'at', 'ta', 'ab', 'ba', 'as', 'se', 'e$'])
     tok.set_prefix_pad('^')
     self.assertEqual(tok.get_prefix_pad(), '^')
     self.assertEqual(
         tok.tokenize('database'),
         ['^d', 'da', 'at', 'ta', 'ab', 'ba', 'as', 'se', 'e$'])
 def test_set_prefix_pad_invalid2(self):
     qg = QgramTokenizer()
     qg.set_prefix_pad('###')
 def test_set_prefix_pad_invalid1(self):
     qg = QgramTokenizer()
     qg.set_prefix_pad(10)