assertEquals(Collections.<String, Integer>emptyMap(), bimap);
    assertEquals(Collections.<Integer, String>emptyMap(), bimap.inverse());
  }

  public void testFromHashMap() {
    Map<String, Integer> hashMap = new LinkedHashMap<>();
    hashMap.put("one", 1);
    hashMap.put("two", 2);
    ImmutableBiMap<String, Integer> bimap = ImmutableBiMap.copyOf(hashMap);