OrderByTestIT.java 文件源码

@Test
public void testChildAddedEvents() throws InterruptedException {
  DatabaseReference ref = IntegrationTestUtils.getRandomNode(masterApp) ;

  Map<String, Object> initial =
      new MapBuilder()
          .put("a", MapBuilder.of("value", 5L))
          .put("c", MapBuilder.of("value", 3L))
          .build();

  final List<String> snapshotNames = new ArrayList<>();
  final List<String> prevNames = new ArrayList<>();
  final Semaphore semaphore = new Semaphore(0);
  final ChildEventListener testListener =
      ref.orderByChild("value")
          .addChildEventListener(
              new TestChildEventListener() {
                @Override
                public void onChildAdded(DataSnapshot snap, String prevName) {
                  snapshotNames.add(snap.getKey());
                  prevNames.add(prevName);
                  semaphore.release();
                }
              });

  ref.setValueAsync(initial);
  TestHelpers.waitFor(semaphore, 2);
  Assert.assertEquals(Arrays.asList("c", "a"), snapshotNames);
  Assert.assertEquals(Arrays.asList(null, "c"), prevNames);

  Map<String, Object> updates = new HashMap<>();
  updates.put("b", MapBuilder.of("value", 4));
  updates.put("d", MapBuilder.of("value", 2));
  ref.updateChildrenAsync(updates);

  TestHelpers.waitFor(semaphore, 2);
  Assert.assertEquals(Arrays.asList("c", "a", "d", "b"), snapshotNames);
  Assert.assertEquals(Arrays.asList(null, "c", null, "c"), prevNames);
  ref.removeEventListener(testListener);
}