public void DeserializationOfExtractorWeird()
        {
            XmlHelper.AddType(typeof(WeirdRuleNode));
            XElement      element = XElement.Parse("<member name='field'><required /><weird /></member>");
            IExtratorNode rule    = XmlHelper.GetExtractorNode(element);

            Assert.That(rule, Is.TypeOf <MemberExtractorNode>());
            MemberExtractorNode extractor = (MemberExtractorNode)rule;

            Assert.That(extractor.RuleNodes, Has.Count.EqualTo(2));
            Assert.That(extractor.RuleNodes[0], Is.InstanceOf <RequiredRuleNode>());
            Assert.That(extractor.RuleNodes[1], Is.InstanceOf <WeirdRuleNode>());
        }