@Test
public void testCloneMapContext() throws Exception {

  TaskID taskId = new TaskID(jobId, TaskType.MAP, 0);
  TaskAttemptID taskAttemptid = new TaskAttemptID(taskId, 0);
  MapContext<IntWritable, IntWritable, IntWritable, IntWritable> mapContext =
  new MapContextImpl<IntWritable, IntWritable, IntWritable, IntWritable>(
      conf, taskAttemptid, null, null, null, null, null);
  Mapper<IntWritable, IntWritable, IntWritable, IntWritable>.Context mapperContext = 
    new WrappedMapper<IntWritable, IntWritable, IntWritable, IntWritable>().getMapContext(
        mapContext);
  ContextFactory.cloneMapContext(mapperContext, conf, null, null);
}