anchor.diff:        expect(actual, expected);
       });
       test('duplicate namespace', () {
  -      var builder = new XmlBuilder(optimizeNamespaces: false);
  +      var builder = new XmlBuilder();
         builder.element('element', nest: () {
           builder.namespace('http://1.foo.com/', 'foo');
           builder.element('inner', nest: () {
  
positive.code:           '</element>';
        expect(actual, expected);
      });
      test('duplicate namespace optimized', () {
        var builder = new XmlBuilder(optimizeNamespaces: true);
        builder.element('element', nest: () {
          builder.namespace('http://1.foo.com/', 'foo');
  
negative.code:       var expected = '<element />';
        expect(actual, expected);
      });
      test('conflicting namespace', () {
        var builder = new XmlBuilder();
        builder.element('element', nest: () {
          builder.namespace('http://1.foo.com/', 'foo');
          expect(() => builder.namespace('http://2.foo.com/', 'foo'),
  