public IThrowableRenderer<ILoggingEvent> getThrowableRenderer() {
    return throwableRenderer;
  }
@Test
  public void testAppendThrowable() throws Exception {
    StringBuilder buf = new StringBuilder();
    DummyThrowableProxy tp = new DummyThrowableProxy();
    tp.setClassName("test1");
    tp.setMessage("msg1");
    
    StackTraceElement ste1 = new StackTraceElement("c1", "m1", "f1", 1);
    StackTraceElement ste2 = new StackTraceElement("c2", "m2", "f2", 2);
    
    StackTraceElementProxy[] stepArray = { new StackTraceElementProxy(ste1),
        new StackTraceElementProxy(ste2) };
    tp.setStackTraceElementProxyArray(stepArray);
    DefaultThrowableRenderer renderer = (DefaultThrowableRenderer) layout
        .getThrowableRenderer();

    renderer.render(buf, tp);
    System.out.println(buf.toString());
    String[] result = buf.toString().split(CoreConstants.LINE_SEPARATOR);
    System.out.println(result[0]);
    assertEquals("test1: msg1", result[0]);
    assertEquals(DefaultThrowableRenderer.TRACE_PREFIX + "at c1.m1(f1:1)", result[1]);
  }