map = makeEmptyMap();
      unmappedKey = getKeyNotInPopulatedMap();
    } catch (UnsupportedOperationException e) {
      return;
    }
    assertNull(map.get(unmappedKey));
  }

  public void testGetNull() {
    Map<K, V> map = makeEitherMap();
    if (allowsNullKeys) {
      if (allowsNullValues) {
        // TODO: decide what to test here.
      } else {