assertTrue(underlying.isEmpty());
    assertTrue(map.isEmpty());
    assertTrue(keys.isEmpty());
    assertTrue(values.isEmpty());
    assertTrue(entries.isEmpty());
  }

  public void testTransformEquals() {
    Map<String, Integer> underlying = ImmutableMap.of("a", 0, "b", 1, "c", 2);
    Map<String, Integer> expected = transformValues(underlying, Functions.<Integer>identity());