### Question:
MRApps extends Apps { public static JobId toJobID(String jid) { return TypeConverter.toYarn(JobID.forName(jid)); } if(userClassesTakesPrecedence); static String toString(JobId jid); static JobId toJobID(String jid); static String toString(TaskId tid); static TaskId toTaskID(String tid); 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); @SuppressWarnings("deprecation") static void setClasspath(Map<String, String> environment,
      Configuration conf);  }### Answer:
@Test public void testToJobID() { JobId jid = MRApps.toJobID("job_1_1"); assertEquals(1, jid.getAppId().getClusterTimestamp()); assertEquals(1, jid.getAppId().getId()); assertEquals(1, jid.getId()); }
@Test(expected=IllegalArgumentException.class) public void testJobIDShort() { MRApps.toJobID("job_0_0_0"); }