Runs the test case.
Document doc;
NodeList emList;
Node emNode;
CharacterData emText;
Node nullChild;
doc = (Document) load("hc_staff", false);
emList = doc.getElementsByTagName("em");
emNode = emList.item(0);
emText = (CharacterData) emNode.getFirstChild();
nullChild = emText.getLastChild();
assertNull("nullChild", nullChild);