/**
  * tests if the manual set namespaceprefix 'foo' overwrites the prefix 'rdf' defined in
  * the default_prefixes array.
  */
 function testOverwritingDefaultManual()
 {
     $_SESSION['test'] = 'Overwriting default manual test';
     $model = new MemModel();
     $pars = new N3Parser();
     $model = $pars->parse2model($this->_generateModelString());
     $ser = new RdfSerializer();
     $string = $ser->serialize($model);
     $model2 = new MemModel();
     $model2->load($string);
     $this->assertEqual($model2->parsedNamespaces[RDF_NAMESPACE_URI], 'rdf');
     $model2->addNamespace('foo', RDF_NAMESPACE_URI);
     $this->assertEqual($model2->parsedNamespaces[RDF_NAMESPACE_URI], 'foo');
     $model2->removeNamespace(RDF_NAMESPACE_URI);
     //$this->assertEqual($model2->parsedNamespaces[RDF_NAMESPACE_URI] , null);
 }