LogHelper { public static void error(Logger logger, Throwable e) { if (logger == null) { return; } if (logger.isErrorEnabled()) { logger.error(e); } } private  LogHelper(); static void trace(Logger logger, String msg); static void trace(Logger logger, Throwable throwable); static void trace(Logger logger, String msg, Throwable e); static void debug(Logger logger, String msg); static void debug(Logger logger, Throwable e); static void debug(Logger logger, String msg, Throwable e); static void info(Logger logger, String msg); static void info(Logger logger, Throwable e); static void info(Logger logger, String msg, Throwable e); static void warn(Logger logger, String msg, Throwable e); static void warn(Logger logger, String msg); static void warn(Logger logger, Throwable e); static void error(Logger logger, Throwable e); static void error(Logger logger, String msg); static void error(Logger logger, String msg, Throwable e);  }
@Test public void testError() throws Exception { Logger logger = Mockito.mock(Logger.class); when(logger.isErrorEnabled()).thenReturn(true); LogHelper.error(logger, "error"); verify(logger).error("error"); Throwable t = new RuntimeException(); LogHelper.error(logger, t); verify(logger).error(t); LogHelper.error(logger, "error", t); verify(logger).error("error", t); }