message: More test cases and comments
diff: @@ -54,7 +54,8 @@ UnicodeType Utf8Proc::Analyze(const char *s, size_t len, UnicodeInvalidReason *i
  return UnicodeType::INVALID;
  }
  if ((utf8char & 0x1FFF800) == 0xD800) {
  - /* low or high surrogate encoded as UTF-8 */
  + /* Unicode characters from U+D800 to U+DFFF are surrogate
  + characters used by UTF-16 which are invalid in UTF-8 */
  AssignInvalidUTF8Reason(invalid_reason, invalid_pos, first_pos_seq, UnicodeInvalidReason::INVALID_UNICODE);
  return UnicodeType::INVALID;
  }
  