readSedMLFromFile doesn't properly handle XML text nodes in newXML

[jonrkarr]

This is an edge case, but since SED-ML is divorced from the details of particular model formats, adding a text node could be a valid operation in a model format.

Example:

<?xml version="1.0" encoding="UTF-8"?>
<sedML xmlns="http://sed-ml.org/sed-ml/level1/version3" level="1" version="3">
  <listOfModels>
    <model id="model" language="urn:sedml:language:sbml" source="model.sbml">
      <listOfChanges>
        <addXML target="/sbml:sbml/sbml:model[id=&apos;b&apos;]/sbml:listOfParameters">
          <newXML>1.9</newXML>
        </addXML>
      </listOfChanges>
    </model>
  </listOfModels>
</sedML>

Here's how libSED-ML behaves on this example:

• XMLNode_convertXMLNodeToString and XMLNode_convertStringToXMLNode correctly round trip 1.9
• writeSedMLToString can export text nodes
• readSedMLFromFile does not correctly import this. newXML is null and no error is raised.

I expected newXML to be text node with value 1.9.