code: @Test public void testSuccessLogger(){
    Logger successLogger=mock(Logger.class);
    FailsafeLogger failsafeLogger=new FailsafeLogger(successLogger);
    failsafeLogger.error("error");
    failsafeLogger.warn("warn");
    failsafeLogger.info("info");
    failsafeLogger.debug("debug");
    failsafeLogger.trace("info");
    verify(successLogger).error(anyString());
    verify(successLogger).warn(anyString());
    verify(successLogger).info(anyString());
    verify(successLogger).debug(anyString());
    verify(successLogger).trace(anyString());
    failsafeLogger.error(new Exception("error"));
    failsafeLogger.warn(new Exception("warn"));
    failsafeLogger.info(new Exception("info"));
    failsafeLogger.debug(new Exception("debug"));
    failsafeLogger.trace(new Exception("trace"));
    failsafeLogger.error("error",new Exception("error"));
    failsafeLogger.warn("warn",new Exception("warn"));
    failsafeLogger.info("info",new Exception("info"));
    failsafeLogger.debug("debug",new Exception("debug"));
    failsafeLogger.trace("trace",new Exception("trace"));
  }
  