}
            },
            Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  public void testUniqueIndexIterator() {
    ImmutableMap<Integer, String> outputMap =
        Maps.uniqueIndex(
            INT_TO_STRING_MAP.values().iterator(), Functions.forMap(INT_TO_STRING_MAP.inverse()));