}

  @Override
  protected Map<K, V> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    BiMap<K, V> bimap = (BiMap<K, V>) map;

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());

  }

  @Override
  protected Map<K, V> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    BiMap<K, V> bimap = (BiMap<K, V>) map;

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());

  }

  @Override
  protected SortedMap<K, V> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

  }

  @Override
  protected Map<K, V> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }