anchor.diff:                  XmlDocument document, int Function() splitter)
               callback) {
         group(title, () {
  -        final string = XmlDocument.parse(input).toXmlString(pretty: true);
  +        test('empty', () {
  +          callback('', <XmlEvent>[], XmlDocument([]), () => 0);
  +        });
  +        final string = XmlDocument.parse(input).toXmlString();
           for (var i = string.length; i > 0; i ~/= 2) {
             test('chunks sized $i', () {
               final events = parseEvents(string).toList(growable: false);
  
positive.code:           .where((event) =>
                event.parentEvent != null && event is! XmlEndElementEvent)
            .toList();
        final expected =
            const XmlNodeCodec().encode(document.rootElement.children);
        expect(actual, expected);
      });
    });
    group('normalizeEvents', () {
  
negative.code: import 'dart:convert';
  import 'dart:math' show min, Random;
  
  import 'package:meta/meta.dart';
  import 'package:test/test.dart';
  import 'package:xml/xml.dart';
  import 'package:xml/xml_events.dart';
  