xs:key, why is validation passing when key value is not member of key reference?

Question

I am interested in defining a key constraint in my Xsd. It is my understanding that using xs:key should constrain the value used to a member of a referenced list of values.<

Answer 1

As usual, after a good night's rest and a fresh look, spotted no fewer than 2 errors in this exercise.

1. First error, validating identity constraints is an explicit process, induced via XmlSchemaValidationFlags.ProcessIdentityConstraints set by XmlReaderSettings.ValidationFlag, and
2. second error, msdn sample contains an error in schema, should read .

Full working sample is as follows,

Xml sample

simple validator

[TestMethod]
public void Test_Schema()
{
    string schemaFileName = @"sampleSchema.xsd";
    string xmlFileName = @"sampleXml.xml";

    XmlSchema schema = 
        XmlSchema.Read(
        File.OpenText(schemaFileName), 
        (o, e) => { throw new Exception("BOOM"); });

    XmlReaderSettings settings = new XmlReaderSettings
    {
        ValidationType = ValidationType.Schema,
        ValidationFlags = 
            XmlSchemaValidationFlags.ProcessInlineSchema | 
            XmlSchemaValidationFlags.ProcessSchemaLocation | 
            XmlSchemaValidationFlags.ReportValidationWarnings | 

            // d'oh! explicit flag for processing identity constraints!
            XmlSchemaValidationFlags.ProcessIdentityConstraints,
    };
    settings.Schemas.Add(schema);
    settings.ValidationEventHandler += 
        (o, e) => { throw new Exception("CRASH"); };

    XmlReader reader = XmlReader.Create(xmlFileName, settings);
    while (reader.Read()) { }
}