Test how the XML serializer manages startEntity() and endEntity() SAX events. The XML serializer only ouputs the characters events received between these two events, and totally ignores the startElement() and endElement() events.

• Bogus result: a pipeline with just a file generator followed by an XML serializer. The file references and entity containing XML markup.
• Correct result: a XSL performing an identity transformation is inserted between the generator and the serializer. It has the effect of removing the startEntity() and endEntity() events from the SAX stream, and the XML serializer therefore correcly does its job.