for (int i = 0; i < len; i++) {
      buffer.putChar(input.charAt(i));
    }
    return hashBytes(buffer.array());
  }

  @Override
  public HashCode hashString(CharSequence input, Charset charset) {
    return hashBytes(input.toString().getBytes(charset));
  }

  @Override
  public abstract HashCode hashBytes(byte[] input, int off, int len);

  @Override

    assertEquals(
        hashFunction.hashUnencodedChars(string),
        hashFunction.newHasher().putUnencodedChars(string).hash());
    for (Charset charset : CHARSETS) {
      assertEquals(
          hashFunction.hashString(string, charset),
          hashFunction.newHasher().putString(string, charset).hash());
    }
  }

  /**
   * This verifies that putUnencodedChars(String) and hashUnencodedChars(String) are equivalent,

    assertEquals(
        hashFunction.hashUnencodedChars(string),
        hashFunction.newHasher().putUnencodedChars(string).hash());
    for (Charset charset : CHARSETS) {
      assertEquals(
          hashFunction.hashString(string, charset),
          hashFunction.newHasher().putString(string, charset).hash());
    }
  }

  /**
   * This verifies that putUnencodedChars(String) and hashUnencodedChars(String) are equivalent,