for (int i = 0; i < chars.length; i++) {
      chars[i] = random.nextBoolean() ? randomLowSurrogate(random) : randomHighSurrogate(random);
    }
    String string = new String(chars);
    assertEquals(
        hashFunction.hashUnencodedChars(string),
        hashFunction.newHasher().putUnencodedChars(string).hash());
  }

  static char randomLowSurrogate(Random random) {
    return (char)
        (Character.MIN_LOW_SURROGATE