assertThat(second.escape("The Quick Brown Fox!")).isEqualTo("Xhe-Xuick-Xrown-Xox$");
  }

  // A trivial non-optimized escaper for testing.
  static CharEscaper createSimpleCharEscaper(ImmutableMap<Character, char[]> replacementMap) {
    return new CharEscaper() {
      @Override
      protected char[] escape(char c) {
        return replacementMap.get(c);
      }
    };
  }