@Test
  public void putAll() {
    User batMan = newUser("batMan");
    User spiderMan = newUser("spiderMan");
    User superMan = newUser("superMan");

    Map<String, User> userMap = getUsersAsMap(batMan, spiderMan, superMan);

    assertThat(users.keySet().containsAll(userMap.keySet())).isFalse();
    assertThat(users.values().containsAll(userMap.values())).isFalse();

    usersTemplate.putAll(userMap);

    assertThat(users.keySet().containsAll(userMap.keySet())).isTrue();
    assertThat(users.values().containsAll(userMap.values())).isTrue();
  }