public void testLog() {
    MDC.put("key", "value1");
    
    logger.trace("Trace level can be noisy");
    logger.debug("Entering application");
    logger.info("Violets are blue");
    logger.warn("Here is a warning");
    logger.error("Exiting application", new Exception("just testing"));
    
    MDC.remove("key");
  }
A test case that issues the typical calls
that an application using log4j 1.2 would do.

@author Ceki G&uuml;lc&uuml;
@author S&eacute;bastien Pennec
log4j-over-slf4j/compatibility/src/main/java/test/Log4j12Calls.java