@Test(timeout = 1000)
  public void testPutAll() {
    SortedMapWritable map1 = new SortedMapWritable();
    SortedMapWritable map2 = new SortedMapWritable();
    map1.put(new Text("key"), new Text("value"));
    map2.putAll(map1);

    assertEquals("map1 entries don't match map2 entries", map1, map2);
    assertTrue(
        "map2 doesn't have class information from map1",
        map2.classToIdMap.containsKey(Text.class) && map2.idToClassMap.containsValue(Text.class));
  }