### Question:
MRApps extends Apps { public static String getJobFile(Configuration conf, String user, org.apache.hadoop.mapreduce.JobID jobId) { Path jobFile = new Path(MRApps.getStagingAreaDir(conf, user), jobId.toString() + Path.SEPARATOR + MRConstants.JOB_CONF_FILE); return jobFile.toString(); }  static String toString(JobId jid); static JobId toJobID(String jid); static JobId toJobID(String prefix, String s, Iterator<String> it); static String toString(TaskId tid); static TaskId toTaskID(String tid); static TaskId toTaskID(String prefix, String s, Iterator<String> it); static String toString(TaskAttemptId taid); static TaskAttemptId toTaskAttemptID(String taid); static String taskSymbol(TaskType type); static TaskType taskType(String symbol); static TaskAttemptStateUI taskAttemptState(String attemptStateStr); static void setInitialClasspath(
      Map<String, String> environment); static void addToClassPath(
      Map<String, String> environment, String fileName); static Path getStagingAreaDir(Configuration conf, String user); static String getJobFile(Configuration conf, String user, 
      org.apache.hadoop.mapreduce.JobID jobId); static final String JOB; static final String TASK; static final String ATTEMPT; static final String CLASSPATH; }### Answer:
@Test public void testGetJobFileWithUser() { Configuration conf = new Configuration(); conf.set(MRConstants.APPS_STAGING_DIR_KEY, "/my/path/to/staging"); String jobFile = MRApps.getJobFile(conf, "dummy-user", new JobID("dummy-job", 12345)); assertNotNull("getJobFile results in null.", jobFile); assertEquals("jobFile with specified user is not as expected.", "/my/path/to/staging/dummy-user/.staging/job_dummy-job_12345/job.xml", jobFile); }