public void testHelloWorldDebug() throws Exception {
final List<String> knownVariables = new ArrayList<String>();
MVELRuntime.resetDebugger();
MVELDebugHandler.setDebugMode(true);
MVELRuntime.setThreadDebugger(new Debugger() {
public int onBreak(Frame frame) {
System.out.println("onBreak");
for (String var: frame.getFactory().getKnownVariables()) {
System.out.println(" " + var);
knownVariables.add(var);