Runs the test case.
Document doc;
DocumentType docType;
NamedNodeMap entities;
Entity entity;
String nullNS = null;
doc = (Document) load("staffNS", false);
docType = doc.getDoctype();
entities = docType.getEntities();
assertNotNull("entitiesNotNull", entities);
entity = (Entity) entities.getNamedItemNS(nullNS, "ent1");
assertNull("entityNull", entity);