@Test
public void testTrace() throws Exception {

    Logger logger = Mockito.mock(Logger.class);
    when(logger.isTraceEnabled()).thenReturn(true);
    LogHelper.trace(logger, "trace");
    verify(logger).trace("trace");
    Throwable t = new RuntimeException();
    LogHelper.trace(logger, t);
    verify(logger).trace(t);
    LogHelper.trace(logger, "trace", t);
    verify(logger).trace("trace", t);
}