* Object)} when the key isn't present, since {@code ~insertionIndex} is equal to {@code -1 -
     * insertionIndex}.
     */
    INVERTED_INSERTION_INDEX {
      @Override
      public int resultIndex(int higherIndex) {
        return ~higherIndex;
      }
    };

    abstract int resultIndex(int higherIndex);
  }

  /**

    switch (absentBehavior) {
      case NEXT_LOWER:
        assertEquals(nextHigherIndex - 1, answer);
        return;
      case NEXT_HIGHER:
        assertEquals(nextHigherIndex, answer);
        return;
      case INVERTED_INSERTION_INDEX:
        assertEquals(-1 - nextHigherIndex, answer);
        return;
      default:
        throw new AssertionError();
    }
  }

  public void testWithoutDups() {

    switch (absentBehavior) {
      case NEXT_LOWER:
        assertEquals(nextHigherIndex - 1, answer);
        return;
      case NEXT_HIGHER:
        assertEquals(nextHigherIndex, answer);
        return;
      case INVERTED_INSERTION_INDEX:
        assertEquals(-1 - nextHigherIndex, answer);
        return;
      default:
        throw new AssertionError();
    }
  }

  public void testWithoutDups() {