错误的命名空间上的.net xml架构验证

使用名称空间为http：// mynamespace的 XML模式.如果验证了具有默认命名空间xmlns =“http：// mynamespace”的错误XML文档,则会按预期抛出异常.如果有人更改了命名空间(http：// Wrongnamespace),这个错误的XML将通过验证.

这是使用模式验证的单元测试.方法XSD_NotValid_2无法正常工作：

[TestClass]
public class XSDTest
{
    public System.Xml.XmlReaderSettings ReaderSettings
    {
        get
        {
            string sXSD = "<xsd:schema targetNamespace="http://mynamespace" xmlns="http://mynamespace""
                + " xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">"
            + "<xsd:element name="Root">"
            + "<xsd:complexType>"
                + "<xsd:sequence>"
                    + "<xsd:element name="Child" minOccurs="1" maxOccurs="1" />"
                + "</xsd:sequence>"
             + "</xsd:complexType>"
            + "</xsd:element>"
            + "</xsd:schema>";

            System.Xml.Schema.XmlSchema schema = System.Xml.Schema.XmlSchema.Read(new System.IO.StringReader(sXSD),new System.Xml.Schema.ValidationEventHandler(OnValidationFail));

            System.Xml.XmlReaderSettings readerSettings_Ret = new System.Xml.XmlReaderSettings();
            readerSettings_Ret.ValidationType = System.Xml.ValidationType.Schema;
            readerSettings_Ret.ValidationEventHandler += new System.Xml.Schema.ValidationEventHandler(OnValidationFail);
            readerSettings_Ret.Schemas.Add(schema);

            return readerSettings_Ret;
        }
    }


    private void OnValidationFail(object s,System.Xml.Schema.ValidationEventArgs e)
    {
        throw new OperationCanceledException("Validation error: " + e.Message);
    }

    [TestMethod]
    public void XSD_Valid_Test()
    {
         // Valid elements and valid namespace
        String sXML_Valid = "<?xml version="1.0" encoding="UTF-8"?>"
            + "<Root xmlns="http://mynamespace"><Child /></Root>";
        System.Xml.XmlReader xmlReader_Valid = 
            System.Xml.XmlReader.Create(new System.IO.StringReader(sXML_Valid),this.ReaderSettings);
        while (xmlReader_Valid.Read()) { } // no fail expected
    }

    [TestMethod]
    [ExpectedException(typeof(OperationCanceledException))]
    public void XSD_NotValid_1()
    {
         // No valid elements,while valid namespace
        String sXML_NotValid_1 = "<?xml version="1.0" encoding="UTF-8"?>"
            + "<BadRoot xmlns="http://mynamespace"><Child /></BadRoot>";
        System.Xml.XmlReader xmlReader_NoValid_1 = 
            System.Xml.XmlReader.Create(new System.IO.StringReader(sXML_NotValid_1),this.ReaderSettings);
        while (xmlReader_NoValid_1.Read()) ;
    }

    [TestMethod]
    [ExpectedException(typeof(OperationCanceledException))]
    public void XSD_NotValid_2()
    {
        // No valid elements and no valid namespace
        String sXML_NotValid_2 = "<?xml version="1.0" encoding="UTF-8"?>"
            + "<Root xmlns="http://Wrongnamespace"><NotValidChild /></Root>";
        System.Xml.XmlReader xmlReader_NoValid_2 = 
            System.Xml.XmlReader.Create(new System.IO.StringReader(sXML_NotValid_2),this.ReaderSettings);
        while (xmlReader_NoValid_2.Read()) ;
    }
}

这是正常的行为吗？如何强制正确的命名空间定位？
还有如何在XSD有额外的Root2元素的情况下强制要求Root元素？

readerSettings_Ret.ValidationFlags = XmlSchemaValidationFlags.ReportValidationWarnings;