def test_diacritic_characters (self):
     self.assertEqual(len(self.bfm.diacritic_characters), 0)
     character1 = DiacriticCharacter(self.bfm, 'a')
     self.assertEqual(len(self.bfm.diacritic_characters), 1)
     self.assertTrue(character1 in self.bfm.diacritic_characters)
     character2 = DiacriticCharacter(self.bfm, 'b')
     self.assertEqual(len(self.bfm.diacritic_characters), 2)
     self.assertTrue(character1 in self.bfm.diacritic_characters)
     self.assertTrue(character2 in self.bfm.diacritic_characters)
     character2.delete()
     self.assertEqual(len(self.bfm.diacritic_characters), 1)
     self.assertTrue(character1 in self.bfm.diacritic_characters)
     character1.delete()
     self.assertEqual(len(self.bfm.diacritic_characters), 0)
     character3 = SpacingCharacter(self.bfm, 'c')
     self.assertEqual(len(self.bfm.diacritic_characters), 0)