public RecordingSimpleLogger logLevel(String logLevel) throws Exception {
    System.setProperty(SHOW_THREAD_NAME_KEY, "false");
    System.setProperty(DEFAULT_LOG_LEVEL_KEY, logLevel);

    SimpleLogger.init();
    ((SimpleLoggerFactory) LoggerFactory.getILoggerFactory()).reset();
    return this;
  }
Resets {@link org.slf4j.impl.SimpleLogger} to the new log level.
slf4j/src/test/java/org/slf4j/simple/RecordingSimpleLogger.java