@Test
  public void update() throws Exception {
    ImmutableItem item = item();
    repository.insert(item).getUnchecked();

    check(repository.update(repository.criteria().id(item.id()))
            .addList("foo").updateAll().getUnchecked())
        .is(1);

    check(repository.findAll().fetchAll().getUnchecked()).hasSize(1);
    check(repository.findAll().fetchAll().getUnchecked().get(0).list()).hasAll("foo");
  }
Basic CRUD operations on the top of repository
mongo/test/org/immutables/mongo/fixture/BasicMongoOperationsTest.java