// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <memory>
#include <string>
#include <vector>

#include "src/unicode-decoder.h"
#include "src/unicode-inl.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace v8 {
namespace internal {

namespace {

using Utf8Decoder = unibrow::Utf8Decoder<512>;

void Decode(Utf8Decoder* decoder, const std::string& str) {
  // Put the string in its own buffer on the heap to make sure that
  // AddressSanitizer's heap-buffer-overflow logic can see what's going on.
  std::unique_ptr<char[]> buffer(new char[str.length()]);
  memcpy(buffer.get(), str.data(), str.length());
  decoder->Reset(buffer.get(), str.length());
}

void DecodeNormally(const std::vector<byte>& bytes,
                    std::vector<unibrow::uchar>* output) {
  size_t cursor = 0;
  while (cursor < bytes.size()) {
    output->push_back(
        unibrow::Utf8::ValueOf(bytes.data() + cursor, bytes.size(), &cursor));
  }
}

void DecodeIncrementally(const std::vector<byte>& bytes,
                         std::vector<unibrow::uchar>* output) {
  unibrow::Utf8::Utf8IncrementalBuffer buffer = 0;
  for (auto b : bytes) {
    unibrow::uchar result = unibrow::Utf8::ValueOfIncremental(b, &buffer);
    if (result != unibrow::Utf8::kIncomplete) {
      output->push_back(result);
    }
  }
  unibrow::uchar result = unibrow::Utf8::ValueOfIncrementalFinish(&buffer);
  if (result != unibrow::Utf8::kBufferEmpty) {
    output->push_back(result);
  }
}

}  // namespace

TEST(UnicodeTest, ReadOffEndOfUtf8String) {
  Utf8Decoder decoder;

  // Not enough continuation bytes before string ends.
  Decode(&decoder, "\xE0");
  Decode(&decoder, "\xED");
  Decode(&decoder, "\xF0");
  Decode(&decoder, "\xF4");
}

TEST(UnicodeTest, IncrementalUTF8DecodingVsNonIncrementalUtf8Decoding) {
  // Unfortunately, V8 has two UTF-8 decoders. This test checks that they
  // produce the same result. This test was inspired by
  // https://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt .
  typedef struct {
    std::vector<byte> bytes;
    std::vector<unibrow::uchar> unicode_expected;
  } TestCase;

  TestCase data[] = {
      // Correct UTF-8 text.
      {{0xce, 0xba, 0xe1, 0xbd, 0xb9, 0xcf, 0x83, 0xce, 0xbc, 0xce, 0xb5},
       {0x3ba, 0x1f79, 0x3c3, 0x3bc, 0x3b5}},

      // First possible sequence of a certain length:
      // 1 byte
      {{0x00}, {0x0}},
      // 2 bytes
      {{0xc2, 0x80}, {0x80}},
      // 3 bytes
      {{0xe0, 0xa0, 0x80}, {0x800}},
      // 4 bytes
      {{0xf0, 0x90, 0x80, 0x80}, {0x10000}},
      // 5 bytes (not supported)
      {{0xf8, 0x88, 0x80, 0x80, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6 bytes (not supported)
      {{0xfc, 0x84, 0x80, 0x80, 0x80, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Last possible sequence of certain length:
      // 1 byte
      {{0x7f}, {0x7f}},
      // 2 bytes
      {{0xdf, 0xbf}, {0x7ff}},
      // 3 bytes
      {{0xef, 0xbf, 0xbf}, {0xffff}},
      // 4 bytes (this sequence is not a valid code point)
      {{0xf7, 0xbf, 0xbf, 0xbf}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 5 bytes (not supported)
      {{0xfb, 0xbf, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6 bytes (not supported)
      {{0xfd, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // Other boundary conditions:
      {{0xed, 0x9f, 0xbf}, {0xd7ff}},
      {{0xee, 0x80, 0x80}, {0xe000}},
      // U+fffd (invalid code point)
      {{0xef, 0xbf, 0xbd}, {0xfffd}},
      // U+10ffff (last valid code point)
      {{0xf4, 0x8f, 0xbf, 0xbf}, {0x10ffff}},
      // First invalid (too large) code point
      {{0xf4, 0x90, 0x80, 0x80}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Malformed sequences:
      // Unexpected continuation bytes:
      // First continuation byte
      {{0x80}, {0xfffd}},
      // Last continuation byte
      {{0xbf}, {0xfffd}},
      // 2 continuation bytes
      {{0x80, 0xbf}, {0xfffd, 0xfffd}},
      // 3 continuation bytes
      {{0x80, 0xbf, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      // 4 continuation bytes
      {{0x80, 0xbf, 0x80, 0xbf}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 5 continuation bytes
      {{0x80, 0xbf, 0x80, 0xbf, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6 continuation bytes
      {{0x80, 0xbf, 0x80, 0xbf, 0x80, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 7 continuation bytes
      {{0x80, 0xbf, 0x80, 0xbf, 0x80, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // Sequence of all 64 possible continuation bytes
      {{0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a,
        0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95,
        0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0,
        0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab,
        0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
        0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // Using each possible continuation byte in a two-byte sequence:
      {{0xd0, 0x80, 0xd0, 0x81, 0xd0, 0x82, 0xd0, 0x83, 0xd0, 0x84, 0xd0, 0x85,
        0xd0, 0x86, 0xd0, 0x87, 0xd0, 0x88, 0xd0, 0x89, 0xd0, 0x8a, 0xd0, 0x8b,
        0xd0, 0x8c, 0xd0, 0x8d, 0xd0, 0x8e, 0xd0, 0x8f, 0xd0, 0x90, 0xd0, 0x91,
        0xd0, 0x92, 0xd0, 0x93, 0xd0, 0x94, 0xd0, 0x95, 0xd0, 0x96, 0xd0, 0x97,
        0xd0, 0x98, 0xd0, 0x99, 0xd0, 0x9a, 0xd0, 0x9b, 0xd0, 0x9c, 0xd0, 0x9d,
        0xd0, 0x9e, 0xd0, 0x9f, 0xd0, 0xa0, 0xd0, 0xa1, 0xd0, 0xa2, 0xd0, 0xa3,
        0xd0, 0xa4, 0xd0, 0xa5, 0xd0, 0xa6, 0xd0, 0xa7, 0xd0, 0xa8, 0xd0, 0xa9,
        0xd0, 0xaa, 0xd0, 0xab, 0xd0, 0xac, 0xd0, 0xad, 0xd0, 0xae, 0xd0, 0xaf,
        0xd0, 0xb0, 0xd0, 0xb1, 0xd0, 0xb2, 0xd0, 0xb3, 0xd0, 0xb4, 0xd0, 0xb5,
        0xd0, 0xb6, 0xd0, 0xb7, 0xd0, 0xb8, 0xd0, 0xb9, 0xd0, 0xba, 0xd0, 0xbb,
        0xd0, 0xbc, 0xd0, 0xbd, 0xd0, 0xbe, 0xd0, 0xbf},
       {0x400, 0x401, 0x402, 0x403, 0x404, 0x405, 0x406, 0x407, 0x408, 0x409,
        0x40a, 0x40b, 0x40c, 0x40d, 0x40e, 0x40f, 0x410, 0x411, 0x412, 0x413,
        0x414, 0x415, 0x416, 0x417, 0x418, 0x419, 0x41a, 0x41b, 0x41c, 0x41d,
        0x41e, 0x41f, 0x420, 0x421, 0x422, 0x423, 0x424, 0x425, 0x426, 0x427,
        0x428, 0x429, 0x42a, 0x42b, 0x42c, 0x42d, 0x42e, 0x42f, 0x430, 0x431,
        0x432, 0x433, 0x434, 0x435, 0x436, 0x437, 0x438, 0x439, 0x43a, 0x43b,
        0x43c, 0x43d, 0x43e, 0x43f}},

      // Lonely first bytes:
      // All 32 first bytes of 32-byte sequences, each followed by a space
      // (generates 32 invalid char + space sequences.
      {{0xc0, 0x20, 0xc1, 0x20, 0xc2, 0x20, 0xc3, 0x20, 0xc4, 0x20, 0xc5,
        0x20, 0xc6, 0x20, 0xc7, 0x20, 0xc8, 0x20, 0xc9, 0x20, 0xca, 0x20,
        0xcb, 0x20, 0xcc, 0x20, 0xcd, 0x20, 0xce, 0x20, 0xcf, 0x20, 0xd0,
        0x20, 0xd1, 0x20, 0xd2, 0x20, 0xd3, 0x20, 0xd4, 0x20, 0xd5, 0x20,
        0xd6, 0x20, 0xd7, 0x20, 0xd8, 0x20, 0xd9, 0x20, 0xda, 0x20, 0xdb,
        0x20, 0xdc, 0x20, 0xdd, 0x20, 0xde, 0x20, 0xdf, 0x20},
       {0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20}},
      // All 16 first bytes of 3-byte sequences, each followed by a space
      // (generates 16 invalid char + space sequences):
      {{0xe0, 0x20, 0xe1, 0x20, 0xe2, 0x20, 0xe3, 0x20, 0xe4, 0x20, 0xe5,
        0x20, 0xe6, 0x20, 0xe7, 0x20, 0xe8, 0x20, 0xe9, 0x20, 0xea, 0x20,
        0xeb, 0x20, 0xec, 0x20, 0xed, 0x20, 0xee, 0x20, 0xef, 0x20},
       {0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20}},
      // All 8 first bytes of 4-byte sequences, each followed by a space
      // (generates 8 invalid char + space sequences):
      {{0xf0, 0x20, 0xf1, 0x20, 0xf2, 0x20, 0xf3, 0x20, 0xf4, 0x20, 0xf5, 0x20,
        0xf6, 0x20, 0xf7, 0x20},
       {0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20,
        0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20}},
      // All 4 first bytes of 5-byte sequences (not supported), each followed by
      // a space (generates 4 invalid char + space sequences):
      {{0xf8, 0x20, 0xf9, 0x20, 0xfa, 0x20, 0xfb, 0x20},
       {0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20, 0xfffd, 0x20}},
      // All 2 first bytes of 6-byte sequences (not supported), each followed by
      // a space (generates 2 invalid char + space sequences):
      {{0xfc, 0x20, 0xfd, 0x20}, {0xfffd, 0x20, 0xfffd, 0x20}},

      // Sequences with last continuation byte missing. Normally the whole
      // incomplete sequence generates a single invalid character (exceptions
      // explained below).

      // 2-byte sequences with last byte missing
      {{0xc0}, {0xfffd}},
      {{0xdf}, {0xfffd}},
      // 3-byte sequences with last byte missing.
      {{0xe8, 0x80}, {0xfffd}},
      {{0xe0, 0xbf}, {0xfffd}},
      {{0xef, 0xbf}, {0xfffd}},
      // Start of an overlong sequence. The first "maximal subpart" is the first
      // byte; it creates an invalid character. Each following byte generates an
      // invalid character too.
      {{0xe0, 0x80}, {0xfffd, 0xfffd}},
      // 4-byte sequences with last byte missing
      {{0xf1, 0x80, 0x80}, {0xfffd}},
      {{0xf4, 0x8f, 0xbf}, {0xfffd}},
      // Start of an overlong sequence. The first "maximal subpart" is the first
      // byte; it creates an invalid character. Each following byte generates an
      // invalid character too.
      {{0xf0, 0x80, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      // 5-byte sequences (not supported) with last byte missing
      {{0xf8, 0x80, 0x80, 0x80}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfb, 0xbf, 0xbf, 0xbf}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6-byte sequences (not supported) with last byte missing
      {{0xfc, 0x80, 0x80, 0x80, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfd, 0xbf, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Concatenation of incomplete sequences: above incomplete sequences
      // concatenated.
      {{0xc0, 0xdf, 0xe8, 0x80, 0xe0, 0xbf, 0xef, 0xbf, 0xe0, 0x80,
        0xf1, 0x80, 0x80, 0xf4, 0x8f, 0xbf, 0xf0, 0x80, 0x80, 0xf8,
        0x80, 0x80, 0x80, 0xfb, 0xbf, 0xbf, 0xbf, 0xfc, 0x80, 0x80,
        0x80, 0x80, 0xfd, 0xbf, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Incomplete sequence tests repeated with a space after the incomplete
      // sequence.

      // 2-byte sequences with last byte missing
      {{0xc0, 0x20}, {0xfffd, 0x20}},
      {{0xdf, 0x20}, {0xfffd, 0x20}},
      // 3-byte sequences with last byte missing
      {{0xe8, 0x80, 0x20}, {0xfffd, 0x20}},
      {{0xe0, 0xbf, 0x20}, {0xfffd, 0x20}},
      {{0xef, 0xbf, 0x20}, {0xfffd, 0x20}},
      // Start of overlong 3-byte sequence with last byte missing
      {{0xe0, 0x80, 0x20}, {0xfffd, 0xfffd, 0x20}},
      // 4-byte sequences with last byte missing
      {{0xf1, 0x80, 0x80, 0x20}, {0xfffd, 0x20}},
      {{0xf4, 0x8f, 0xbf, 0x20}, {0xfffd, 0x20}},
      // Start of overlong 4-byte sequence with last byte missing
      {{0xf0, 0x80, 0x80, 0x20}, {0xfffd, 0xfffd, 0xfffd, 0x20}},
      // 5-byte sequences (not supported) with last byte missing
      {{0xf8, 0x80, 0x80, 0x80, 0x20}, {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0x20}},
      {{0xfb, 0xbf, 0xbf, 0xbf, 0x20}, {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0x20}},
      // 6-byte sequences (not supported) with last byte missing
      {{0xfc, 0x80, 0x80, 0x80, 0x80, 0x20},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0x20}},
      {{0xfd, 0xbf, 0xbf, 0xbf, 0xbf, 0x20},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0x20}},

      // Impossible bytes
      {{0xfe}, {0xfffd}},
      {{0xff}, {0xfffd}},
      {{0xfe, 0xfe, 0xff, 0xff}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // Lead-byte-like bytes which aren't valid lead bytes.
      {{0xc0}, {0xfffd}},
      {{0xc0, 0xaa}, {0xfffd, 0xfffd}},
      {{0xc1}, {0xfffd}},
      {{0xc1, 0xaa}, {0xfffd, 0xfffd}},
      {{0xf5}, {0xfffd}},
      {{0xf5, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xf6}, {0xfffd}},
      {{0xf6, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xf7}, {0xfffd}},
      {{0xf7, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xf8}, {0xfffd}},
      {{0xf8, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xf9}, {0xfffd}},
      {{0xf9, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfa}, {0xfffd}},
      {{0xfa, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfb}, {0xfffd}},
      {{0xfb, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfc}, {0xfffd}},
      {{0xfc, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfd}, {0xfffd}},
      {{0xfd, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xfe}, {0xfffd}},
      {{0xfe, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xff}, {0xfffd}},
      {{0xff, 0xaa, 0xaa, 0xaa}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Overlong sequences:

      // Overlong encodings for "/"
      {{0xc0, 0xaf}, {0xfffd, 0xfffd}},
      {{0xe0, 0x80, 0xaf}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xf0, 0x80, 0x80, 0xaf}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 5-byte sequence (not supported anyway)
      {{0xf8, 0x80, 0x80, 0x80, 0xaf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6-byte sequence (not supported anyway)
      {{0xfc, 0x80, 0x80, 0x80, 0x80, 0xaf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Maximum overlong sequences
      {{0xc1, 0xbf}, {0xfffd, 0xfffd}},
      {{0xe0, 0x9f, 0xbf}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xf0, 0x8f, 0xbf, 0xbf}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 5-byte sequence (not supported anyway)
      {{0xf8, 0x87, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6-byte sequence (not supported anyway)
      {{0xfc, 0x83, 0xbf, 0xbf, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Overlong encodings for 0
      {{0xc0, 0x80}, {0xfffd, 0xfffd}},
      {{0xe0, 0x80, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xf0, 0x80, 0x80, 0x80}, {0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 5-byte sequence (not supported anyway)
      {{0xf8, 0x80, 0x80, 0x80, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      // 6-byte sequence (not supported anyway)
      {{0xfc, 0x80, 0x80, 0x80, 0x80, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Illegal code positions:

      // Single UTF-16 surrogates
      {{0xed, 0xa0, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xa0, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xad, 0xbf}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xae, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xaf, 0xbf}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xb0, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xbe, 0x80}, {0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xbf, 0xbf}, {0xfffd, 0xfffd, 0xfffd}},

      // Paired surrogates
      {{0xed, 0xa0, 0x80, 0xed, 0xb0, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xa0, 0x80, 0xed, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xad, 0xbf, 0xed, 0xb0, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xad, 0xbf, 0xed, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xae, 0x80, 0xed, 0xb0, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xae, 0x80, 0xed, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xaf, 0xbf, 0xed, 0xb0, 0x80},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},
      {{0xed, 0xaf, 0xbf, 0xed, 0xbf, 0xbf},
       {0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd}},

      // Surrogates with the last byte missing.
      {{0xed, 0xa0}, {0xfffd, 0xfffd}},
      {{0xed, 0xa0}, {0xfffd, 0xfffd}},
      {{0xed, 0xad}, {0xfffd, 0xfffd}},
      {{0xed, 0xae}, {0xfffd, 0xfffd}},
      {{0xed, 0xaf}, {0xfffd, 0xfffd}},
      {{0xed, 0xb0}, {0xfffd, 0xfffd}},
      {{0xed, 0xbe}, {0xfffd, 0xfffd}},
      {{0xed, 0xbf}, {0xfffd, 0xfffd}},

      // Other non-characters
      {{0xef, 0xbf, 0xbe}, {0xfffe}},
      {{0xef, 0xbf, 0xbf}, {0xffff}},
      {{0xef, 0xb7, 0x90, 0xef, 0xb7, 0x91, 0xef, 0xb7, 0x92, 0xef, 0xb7, 0x93,
        0xef, 0xb7, 0x94, 0xef, 0xb7, 0x95, 0xef, 0xb7, 0x96, 0xef, 0xb7, 0x97,
        0xef, 0xb7, 0x98, 0xef, 0xb7, 0x99, 0xef, 0xb7, 0x9a, 0xef, 0xb7, 0x9b,
        0xef, 0xb7, 0x9c, 0xef, 0xb7, 0x9d, 0xef, 0xb7, 0x9e, 0xef, 0xb7, 0x9f,
        0xef, 0xb7, 0xa0, 0xef, 0xb7, 0xa1, 0xef, 0xb7, 0xa2, 0xef, 0xb7, 0xa3,
        0xef, 0xb7, 0xa4, 0xef, 0xb7, 0xa5, 0xef, 0xb7, 0xa6, 0xef, 0xb7, 0xa7,
        0xef, 0xb7, 0xa8, 0xef, 0xb7, 0xa9, 0xef, 0xb7, 0xaa, 0xef, 0xb7, 0xab,
        0xef, 0xb7, 0xac, 0xef, 0xb7, 0xad, 0xef, 0xb7, 0xae, 0xef, 0xb7, 0xaf},
       {0xfdd0, 0xfdd1, 0xfdd2, 0xfdd3, 0xfdd4, 0xfdd5, 0xfdd6, 0xfdd7,
        0xfdd8, 0xfdd9, 0xfdda, 0xfddb, 0xfddc, 0xfddd, 0xfdde, 0xfddf,
        0xfde0, 0xfde1, 0xfde2, 0xfde3, 0xfde4, 0xfde5, 0xfde6, 0xfde7,
        0xfde8, 0xfde9, 0xfdea, 0xfdeb, 0xfdec, 0xfded, 0xfdee, 0xfdef}},
      {{0xf0, 0x9f, 0xbf, 0xbe, 0xf0, 0x9f, 0xbf, 0xbf, 0xf0, 0xaf, 0xbf,
        0xbe, 0xf0, 0xaf, 0xbf, 0xbf, 0xf0, 0xbf, 0xbf, 0xbe, 0xf0, 0xbf,
        0xbf, 0xbf, 0xf1, 0x8f, 0xbf, 0xbe, 0xf1, 0x8f, 0xbf, 0xbf, 0xf1,
        0x9f, 0xbf, 0xbe, 0xf1, 0x9f, 0xbf, 0xbf, 0xf1, 0xaf, 0xbf, 0xbe,
        0xf1, 0xaf, 0xbf, 0xbf, 0xf1, 0xbf, 0xbf, 0xbe, 0xf1, 0xbf, 0xbf,
        0xbf, 0xf2, 0x8f, 0xbf, 0xbe, 0xf2, 0x8f, 0xbf, 0xbf},
       {0x1fffe, 0x1ffff, 0x2fffe, 0x2ffff, 0x3fffe, 0x3ffff, 0x4fffe, 0x4ffff,
        0x5fffe, 0x5ffff, 0x6fffe, 0x6ffff, 0x7fffe, 0x7ffff, 0x8fffe,
        0x8ffff}},
  };

  for (auto test : data) {
    // For figuring out which test fails:
    fprintf(stderr, "test: ");
    for (auto b : test.bytes) {
      fprintf(stderr, "%x ", b);
    }
    fprintf(stderr, "\n");

    std::vector<unibrow::uchar> output_normal;
    DecodeNormally(test.bytes, &output_normal);

    CHECK_EQ(output_normal.size(), test.unicode_expected.size());
    for (size_t i = 0; i < output_normal.size(); ++i) {
      CHECK_EQ(output_normal[i], test.unicode_expected[i]);
    }

    std::vector<unibrow::uchar> output_incremental;
    DecodeIncrementally(test.bytes, &output_incremental);

    CHECK_EQ(output_incremental.size(), test.unicode_expected.size());
    for (size_t i = 0; i < output_incremental.size(); ++i) {
      CHECK_EQ(output_incremental[i], test.unicode_expected[i]);
    }
  }
}

}  // namespace internal
}  // namespace v8