@Test
  public void testApplicationOrderingWithPriority() throws Exception {

    Configuration conf = new Configuration();
    conf.setClass(YarnConfiguration.RM_SCHEDULER, CapacityScheduler.class, ResourceScheduler.class);
    MockRM rm = new MockRM(conf);
    rm.start();
    CapacityScheduler cs = (CapacityScheduler) rm.getResourceScheduler();

    LeafQueue q = (LeafQueue) cs.getQueue("default");
    Assert.assertNotNull(q);

    String host = "127.0.0.1";
    RMNode node = MockNodes.newNodeInfo(0, MockNodes.newResource(16 * GB), 1, host);
    cs.handle(new NodeAddedSchedulerEvent(node));

    // add app 1 start
    ApplicationId appId1 = BuilderUtils.newApplicationId(100, 1);
    ApplicationAttemptId appAttemptId1 = BuilderUtils.newApplicationAttemptId(appId1, 1);

    RMAppAttemptMetrics attemptMetric1 = new RMAppAttemptMetrics(appAttemptId1, rm.getRMContext());
    RMAppImpl app1 = mock(RMAppImpl.class);
    when(app1.getApplicationId()).thenReturn(appId1);
    RMAppAttemptImpl attempt1 = mock(RMAppAttemptImpl.class);
    when(attempt1.getAppAttemptId()).thenReturn(appAttemptId1);
    when(attempt1.getRMAppAttemptMetrics()).thenReturn(attemptMetric1);
    when(app1.getCurrentAppAttempt()).thenReturn(attempt1);

    rm.getRMContext().getRMApps().put(appId1, app1);

    SchedulerEvent addAppEvent1 =
        new AppAddedSchedulerEvent(appId1, "default", "user", null, Priority.newInstance(5));
    cs.handle(addAppEvent1);
    SchedulerEvent addAttemptEvent1 = new AppAttemptAddedSchedulerEvent(appAttemptId1, false);
    cs.handle(addAttemptEvent1);
    // add app1 end

    // add app2 begin
    ApplicationId appId2 = BuilderUtils.newApplicationId(100, 2);
    ApplicationAttemptId appAttemptId2 = BuilderUtils.newApplicationAttemptId(appId2, 1);

    RMAppAttemptMetrics attemptMetric2 = new RMAppAttemptMetrics(appAttemptId2, rm.getRMContext());
    RMAppImpl app2 = mock(RMAppImpl.class);
    when(app2.getApplicationId()).thenReturn(appId2);
    RMAppAttemptImpl attempt2 = mock(RMAppAttemptImpl.class);
    when(attempt2.getAppAttemptId()).thenReturn(appAttemptId2);
    when(attempt2.getRMAppAttemptMetrics()).thenReturn(attemptMetric2);
    when(app2.getCurrentAppAttempt()).thenReturn(attempt2);

    rm.getRMContext().getRMApps().put(appId2, app2);

    SchedulerEvent addAppEvent2 =
        new AppAddedSchedulerEvent(appId2, "default", "user", null, Priority.newInstance(8));
    cs.handle(addAppEvent2);
    SchedulerEvent addAttemptEvent2 = new AppAttemptAddedSchedulerEvent(appAttemptId2, false);
    cs.handle(addAttemptEvent2);
    // add app end

    // Now, the first assignment will be for app2 since app2 is of highest
    // priority
    assertEquals(q.getApplications().size(), 2);
    assertEquals(q.getApplications().iterator().next().getApplicationAttemptId(), appAttemptId2);

    rm.stop();
  }