doTestNull(forPredicate(Predicates.equalTo('c')));
  }

  private void doTestEmpty(CharMatcher matcher) throws Exception {
    reallyTestEmpty(matcher);
    reallyTestEmpty(matcher.negate());
    reallyTestEmpty(matcher.precomputed());
  }

  private void reallyTestEmpty(CharMatcher matcher) throws Exception {
    assertEquals(-1, matcher.indexIn(""));
    assertEquals(-1, matcher.indexIn("", 0));
    try {