TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(emptyMap(), map);
    assertThat(map.comparator()).isEqualTo(SOME_COMPARATOR);
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);