test/Prototypes/UnicodeDecoders.swift

//===--- UnicodeDecoders.swift --------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// RUN: %target-build-swift %s -g -Onone -o %t
// RUN: %target-codesign %t
// RUN: %target-run %t
// REQUIRES: executable_test

// Benchmarking: use the following script with your swift-4-enabled swiftc.
// The BASELINE timings come from the existing standard library Codecs

/* 
  for x in BASELINE FORWARD REVERSE SEQUENCE COLLECTION REVERSE_COLLECTION ; do 
    echo $x
    swiftc -DBENCHMARK -D$x -O -swift-version 4 UnicodeDecoders.swift -o /tmp/u3-$x 
    for i in {1..3}; do
      (time nice -19 /tmp/u3-$x) 2>&1 | grep user
    done
  done
*/

//===----------------------------------------------------------------------===//
extension Unicode.Scalar {
  // Hack providing an efficient API that is available to the standard library
  @usableFromInline
  @inline(__always)
  init(_unchecked x: UInt32) { self = unsafeBitCast(x, to: Unicode.Scalar.self) }
}
//===----------------------------------------------------------------------===//

extension Unicode {
  @_fixed_layout
  public // @testable
  struct _ParsingIterator<
    CodeUnitIterator : IteratorProtocol, 
    Parser: Unicode.Parser
  > where Parser.Encoding.CodeUnit == CodeUnitIterator.Element {
    @inline(__always)
    @inlinable
    public init(codeUnits: CodeUnitIterator, parser: Parser) {
      self.codeUnits = codeUnits
      self.parser = parser
    }
    public var codeUnits: CodeUnitIterator
    public var parser: Parser
  }
}

extension Unicode._ParsingIterator : IteratorProtocol, Sequence {
  @inline(__always)
  @inlinable
  public mutating func next() -> Parser.Encoding.EncodedScalar? {
    switch parser.parseScalar(from: &codeUnits) {
    case let .valid(scalarContent): return scalarContent
    case .error: return Parser.Encoding.encodedReplacementCharacter
    case .emptyInput: return nil
    }
  }
}

extension _UnicodeParser {
  @inlinable // FIXME(sil-serialize-all)
  @inline(__always)
  @discardableResult
  internal static func _parse<I: IteratorProtocol>(
    _ input: inout I,
    repairingIllFormedSequences makeRepairs: Bool = true,
    into output: (Encoding.EncodedScalar)->Void
  ) -> Int
  where I.Element == Encoding.CodeUnit
  {
    var errorCount = 0
    var d = Self()
    while true {
      switch d.parseScalar(from: &input) {
      case let .valid(scalarContent):
        output(scalarContent)
      case .error:
        if _slowPath(!makeRepairs) { return 1 }
        errorCount += 1
        output(Encoding.encodedReplacementCharacter)
      case .emptyInput:
        return errorCount
      }
    }
  }

  @inlinable // FIXME(sil-serialize-all)
  @inline(__always)
  @discardableResult
  public static func _decode<I: IteratorProtocol>(
    _ input: inout I,
    repairingIllFormedSequences makeRepairs: Bool,
    into output: (Unicode.Scalar)->Void
  ) -> Int
  where I.Element == Encoding.CodeUnit
  {
    return _parse(&input, repairingIllFormedSequences: makeRepairs) {
      output(Encoding.decode($0))
    }
  }
}

extension Unicode {
  struct DefaultScalarView<
    CodeUnits: BidirectionalCollection,
    Encoding: Unicode.Encoding
  > where CodeUnits.Element == Encoding.CodeUnit {
    var codeUnits: CodeUnits
    init(
      _ codeUnits: CodeUnits,
      fromEncoding _: Encoding.Type = Encoding.self) {
      self.codeUnits = codeUnits
    }
  }
}

extension Unicode.DefaultScalarView : Sequence {
  struct Iterator {
    var parsing: Unicode._ParsingIterator<
      CodeUnits.Iterator, Encoding.ForwardParser>
  }
  
  func makeIterator() -> Iterator {
    return Iterator(
      parsing: Unicode._ParsingIterator(
        codeUnits: codeUnits.makeIterator(),
        parser: Encoding.ForwardParser()
      ))
  }
}

extension Unicode.DefaultScalarView.Iterator : IteratorProtocol, Sequence {
  mutating func next() -> Unicode.Scalar? {
    return parsing.next().map { Encoding.decode($0) }
  }
}

extension Unicode.DefaultScalarView {
  struct Index {
    var codeUnitIndex: CodeUnits.Index
    var scalar: Unicode.Scalar
    var stride: UInt8
  }
}

extension Unicode.DefaultScalarView.Index : Comparable {
  @inline(__always)
  public static func < (
    lhs: Unicode.DefaultScalarView<CodeUnits,Encoding>.Index,
    rhs: Unicode.DefaultScalarView<CodeUnits,Encoding>.Index
  ) -> Bool {
    return lhs.codeUnitIndex < rhs.codeUnitIndex
  }
  
  @inline(__always)
  public static func == (
    lhs: Unicode.DefaultScalarView<CodeUnits,Encoding>.Index,
    rhs: Unicode.DefaultScalarView<CodeUnits,Encoding>.Index
  ) -> Bool {
    return lhs.codeUnitIndex == rhs.codeUnitIndex
  }
}

extension Unicode.DefaultScalarView : Collection {
  public var startIndex: Index {
    @inline(__always)
    get {
      return index(
        after: Index(
          codeUnitIndex: codeUnits.startIndex,
          scalar: Unicode.Scalar(_unchecked: 0),
          stride: 0)
      )
    }
  }

  public var endIndex: Index {
    @inline(__always)
    get {
      return Index(
        codeUnitIndex: codeUnits.endIndex,
        scalar: Unicode.Scalar(_unchecked: 0),
        stride: 0)
    }
  }

  public subscript(i: Index) -> Unicode.Scalar {
    @inline(__always) get { return i.scalar }
  }

  @inline(__always)
  public func index(after i: Index) -> Index {
    let nextPosition = codeUnits.index(
      i.codeUnitIndex, offsetBy: numericCast(i.stride))
    var i = IndexingIterator(
      _elements: codeUnits, _position: nextPosition
    )
    var d = Encoding.ForwardParser()
    switch d.parseScalar(from: &i) {
    case .valid(let scalarContent):
      return Index(
        codeUnitIndex: nextPosition,
        scalar: Encoding.decode(scalarContent),
        stride: numericCast(scalarContent.count))
    case .error(let stride):
      return Index(
        codeUnitIndex: nextPosition,
        scalar: Unicode.Scalar(_unchecked: 0xfffd),
        stride: numericCast(stride))
    case .emptyInput:
      return endIndex
    }
  }
}

extension Unicode.DefaultScalarView : BidirectionalCollection {
  @inline(__always)
  public func index(before i: Index) -> Index {
    var parser = Encoding.ReverseParser()
    
    var more = codeUnits[..<i.codeUnitIndex].reversed().makeIterator()
    
    switch parser.parseScalar(from: &more) {
    case .valid(let scalarContent):
      let d: Int = -scalarContent.count
      return Index(
        codeUnitIndex: codeUnits.index(i.codeUnitIndex, offsetBy: d),
        scalar: Encoding.decode(scalarContent),
        stride: numericCast(scalarContent.count))
    case .error(let stride):
      let d: Int = -stride
      return Index(
        codeUnitIndex: codeUnits.index(i.codeUnitIndex, offsetBy: d) ,
        scalar: Unicode.Scalar(_unchecked: 0xfffd),
        stride: numericCast(stride))
    case .emptyInput: fatalError("index out of bounds.")
    }
  }
}

#if !BENCHMARK
//===--- testing ----------------------------------------------------------===//
import StdlibUnittest
import SwiftPrivate

func utf32<S : StringProtocol>(_ s: S) -> [UInt32] {
  return s.unicodeScalars.map { $0.value }
}

func checkStringProtocol<S : StringProtocol, Encoding: Unicode.Encoding>(
  _ s: S,
  _ utfStr: [Encoding.CodeUnit],
  encodedAs: Encoding.Type,
  expectingUTF32 expected: [UInt32]
) {
  expectEqualSequence(
    expected, utf32(S(decoding: utfStr, as: Encoding.self)),
    "\(S.self) init(decoding:as:)")

  if !utfStr.contains(0) {
    if Encoding.self == Unicode.UTF8.self {
      var ntbs = utfStr.map { CChar(truncatingIfNeeded: $0) }
      ntbs.append(0)
      expectEqualSequence(
        expected, utf32(S(cString: ntbs)), "\(S.self) init(cString:)")
    }
    
    var ntbs = Array(utfStr); ntbs.append(0)
    expectEqualSequence(
      expected, utf32(S(decodingCString: ntbs, as: Encoding.self)),
      "\(S.self) init(cString:encoding:)"
    )

    s.withCString {
      expectEqual(s, S(cString: $0), "\(S.self) withCString(_:)")
    }
    
    s.withCString(encodedAs: Encoding.self) {
      expectEqual(s, S(decodingCString: $0, as: Encoding.self),
        "\(S.self) withCString(encoding:_:)")
    }
  }
}

func checkDecodeUTF<Codec : UnicodeCodec>(
  _ codec: Codec.Type, _ expectedHead: [UInt32],
  _ expectedRepairedTail: [UInt32], _ utfStr: [Codec.CodeUnit]
) -> AssertionResult {
  var decoded = [UInt32]()
  var expected = expectedHead
  
  func output(_ scalar: UInt32) {
    decoded.append(scalar)
    expectEqual(
      Unicode.Scalar(scalar),
      Codec.decode(Codec.encode(Unicode.Scalar(scalar)!)!))
  }
  
  func output1(_ scalar: Unicode.Scalar) {
    decoded.append(scalar.value)
    expectEqual(scalar, Codec.decode(Codec.encode(scalar)!))
  }
  
  var result = assertionSuccess()
  
  func check<C: Collection>(_ expected: C, _ description: String)
  where C.Element == UInt32
  {
    if !expected.elementsEqual(decoded) {
      if result.description == "" { result = assertionFailure()  }
      result = result.withDescription(" [\(description)]\n")
        .withDescription("expected: \(asHex(expectedHead))\n")
        .withDescription("actual:       \(asHex(decoded))")
    }
    decoded.removeAll(keepingCapacity: true)
  }

  //===--- Tests without repairs ------------------------------------------===//
  do {
    let iterator = utfStr.makeIterator()
    _ = transcode(
      iterator, from: codec, to: Unicode.UTF32.self,
      stoppingOnError: true, into: output)
  }
  check(expected, "legacy, repairing: false")

  do {
    var iterator = utfStr.makeIterator()
    let errorCount = Codec.ForwardParser._decode(
      &iterator, repairingIllFormedSequences: false, into: output1)
    expectEqual(expectedRepairedTail.isEmpty ? 0 : 1, errorCount)
  }
  check(expected, "forward, repairing: false")

  do {
    var iterator = utfStr.reversed().makeIterator()
    let errorCount = Codec.ReverseParser._decode(
      &iterator, repairingIllFormedSequences: false, into: output1)
    if expectedRepairedTail.isEmpty {
      expectEqual(0, errorCount)
      check(expected.reversed(), "reverse, repairing: false")
    }
    else {
      expectEqual(1, errorCount)
      let x = (expected + expectedRepairedTail).reversed()
      expectTrue(
        x.starts(with: decoded),
        "reverse, repairing: false\n\t\(Array(x)) does not start with \(decoded)")
      decoded.removeAll(keepingCapacity: true)
    }
  }

  //===--- Tests with repairs ------------------------------------------===//
  expected += expectedRepairedTail
  do {
    let iterator = utfStr.makeIterator()
    _ = transcode(iterator, from: codec, to: Unicode.UTF32.self,
      stoppingOnError: false, into: output)
  }
  check(expected, "legacy, repairing: true")
  do {
    var iterator = utfStr.makeIterator()
    let errorCount = Codec.ForwardParser._decode(
      &iterator, repairingIllFormedSequences: true, into: output1)
    
    if expectedRepairedTail.isEmpty { expectEqual(0, errorCount) }
    else { expectNotEqual(0, errorCount) }
  }
  check(expected, "forward, repairing: true")
  do {
    var iterator = utfStr.reversed().makeIterator()
    let errorCount = Codec.ReverseParser._decode(
      &iterator, repairingIllFormedSequences: true, into: output1)
    if expectedRepairedTail.isEmpty { expectEqual(0, errorCount) }
    else { expectNotEqual(0, errorCount) }
  }
  check(expected.reversed(), "reverse, repairing: true")
  
  //===--- String/Substring Construction and C-String interop -------------===//
  do {
    let s = String(decoding: utfStr, as: Codec.self)
    checkStringProtocol(
      s, utfStr, encodedAs: Codec.self, expectingUTF32: expected)
  }
  
  do {
    let s0 = "\n" + String(decoding: utfStr, as: Codec.self) + "\n"
    let s = s0.dropFirst().dropLast()
    expectEqualSequence(expected, utf32(s), "Sliced Substring")
    checkStringProtocol(
      s0.dropFirst().dropLast(),
      utfStr, encodedAs: Codec.self, expectingUTF32: expected)
  }

  //===--- Transcoded Scalars ---------------------------------------------===//
  for x in decoded.lazy.map({ Unicode.Scalar($0)! }) {
    expectEqualSequence(
      Unicode.UTF8.encode(x)!,
      Unicode.UTF8.transcode(
        Codec.encode(x)!, from: Codec.self)!
    )
    expectEqualSequence(
      Unicode.UTF16.encode(x)!,
      Unicode.UTF16.transcode(
        Codec.encode(x)!, from: Codec.self)!
    )
    expectEqualSequence(
      Unicode.UTF32.encode(x)!,
      Unicode.UTF32.transcode(
        Codec.encode(x)!, from: Codec.self)!
    )
  }
  
  //===--- Scalar View ----------------------------------------------------===//
  let scalars = Unicode.DefaultScalarView(utfStr, fromEncoding: Codec.self)
  expectEqualSequence(expected, scalars.map { $0.value })
  expectEqualSequence(
    expected.reversed(),
    scalars.reversed().map { $0.value })

  do {
    var x = scalars.makeIterator()
    var j = scalars.startIndex
    while (j != scalars.endIndex) {
      expectEqual(x.next()!, scalars[j])
      j = scalars.index(after: j)
    }
    expectNil(x.next())
  }

  return result
}

func checkDecodeUTF8(
    _ expectedHead: [UInt32],
    _ expectedRepairedTail: [UInt32], _ utf8Str: [UInt8]
) -> AssertionResult {
  return checkDecodeUTF(Unicode.UTF8.self, expectedHead, expectedRepairedTail, utf8Str)
}

func checkDecodeUTF16(
    _ expectedHead: [UInt32],
    _ expectedRepairedTail: [UInt32], _ utf16Str: [UInt16]
) -> AssertionResult {
  return checkDecodeUTF(Unicode.UTF16.self, expectedHead, expectedRepairedTail,
      utf16Str)
}

func checkDecodeUTF32(
    _ expectedHead: [UInt32],
    _ expectedRepairedTail: [UInt32], _ utf32Str: [UInt32]
) -> AssertionResult {
  return checkDecodeUTF(Unicode.UTF32.self, expectedHead, expectedRepairedTail,
      utf32Str)
}

func checkEncodeUTF8(_ expected: [UInt8],
                     _ scalars: [UInt32]) -> AssertionResult {
  var encoded = [UInt8]()
  let output: (UInt8) -> Void = { encoded.append($0) }
  let iterator = scalars.makeIterator()
  let hadError = transcode(
    iterator,
    from: Unicode.UTF32.self,
    to: Unicode.UTF8.self,
    stoppingOnError: true,
    into: output)
  expectFalse(hadError)
  if expected != encoded {
    return assertionFailure()
        .withDescription("\n")
        .withDescription("expected: \(asHex(expected))\n")
        .withDescription("actual:   \(asHex(encoded))")
  }

  return assertionSuccess()
}

//===----------------------------------------------------------------------===//

var UTF32Decoder = TestSuite("UTF32Decoder")

UTF32Decoder.test("Empty") {
  expectTrue(checkDecodeUTF32([], [], []))
}

UTF32Decoder.test("SmokeTest") {
  // U+0041 LATIN CAPITAL LETTER A
  expectTrue(checkDecodeUTF32([ 0x0041 ], [], [ 0x0000_0041 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  expectTrue(checkDecodeUTF32(
      [ 0x0041, 0x0042 ], [],
      [ 0x0000_0041, 0x0000_0042 ]))

  // U+0000 NULL
  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0000 NULL
  expectTrue(checkDecodeUTF32(
      [ 0x0000, 0x0041, 0x0042, 0x0000 ], [],
      [ 0x0000_0000, 0x0000_0041, 0x0000_0042, 0x0000_0000 ]))

  // U+0283 LATIN SMALL LETTER ESH
  expectTrue(checkDecodeUTF32([ 0x0283 ], [], [ 0x0000_0283 ]))

  // U+03BA GREEK SMALL LETTER KAPPA
  // U+1F79 GREEK SMALL LETTER OMICRON WITH OXIA
  // U+03C3 GREEK SMALL LETTER SIGMA
  // U+03BC GREEK SMALL LETTER MU
  // U+03B5 GREEK SMALL LETTER EPSILON
  expectTrue(checkDecodeUTF32(
      [ 0x03ba, 0x1f79, 0x03c3, 0x03bc, 0x03b5 ], [],
      [ 0x0000_03ba, 0x0000_1f79, 0x0000_03c3, 0x0000_03bc, 0x0000_03b5 ]))

  // U+4F8B CJK UNIFIED IDEOGRAPH-4F8B
  // U+6587 CJK UNIFIED IDEOGRAPH-6587
  expectTrue(checkDecodeUTF32(
      [ 0x4f8b, 0x6587 ], [],
      [ 0x0000_4f8b, 0x0000_6587 ]))

  // U+D55C HANGUL SYLLABLE HAN
  // U+AE00 HANGUL SYLLABLE GEUL
  expectTrue(checkDecodeUTF32(
      [ 0xd55c, 0xae00 ], [],
      [ 0x0000_d55c, 0x0000_ae00 ]))

  // U+1112 HANGUL CHOSEONG HIEUH
  // U+1161 HANGUL JUNGSEONG A
  // U+11AB HANGUL JONGSEONG NIEUN
  // U+1100 HANGUL CHOSEONG KIYEOK
  // U+1173 HANGUL JUNGSEONG EU
  // U+11AF HANGUL JONGSEONG RIEUL
  expectTrue(checkDecodeUTF32(
      [ 0x1112, 0x1161, 0x11ab, 0x1100, 0x1173, 0x11af ], [],
      [ 0x0000_1112, 0x0000_1161, 0x0000_11ab, 0x0000_1100, 0x0000_1173,
        0x0000_11af ]))

  // U+D7FF (unassigned)
  expectTrue(checkDecodeUTF16([ 0xd7ff ], [], [ 0x0000_d7ff ]))

  // U+E000 (private use)
  expectTrue(checkDecodeUTF16([ 0xe000 ], [], [ 0x0000_e000 ]))

  // U+FFFD REPLACEMENT CHARACTER
  expectTrue(checkDecodeUTF16([ 0xfffd ], [], [ 0x0000_fffd ]))

  // U+FFFF (noncharacter)
  expectTrue(checkDecodeUTF16([ 0xffff ], [], [ 0x0000_ffff ]))

  // U+10000 LINEAR B SYLLABLE B008 A
  expectTrue(checkDecodeUTF32([ 0x00010000 ], [], [ 0x0001_0000 ]))

  // U+10100 AEGEAN WORD SEPARATOR LINE
  expectTrue(checkDecodeUTF32([ 0x00010100 ], [], [ 0x0001_0100 ]))

  // U+103FF (unassigned)
  expectTrue(checkDecodeUTF32([ 0x000103ff ], [], [ 0x0001_03ff ]))

  // U+1D800 (unassigned)
  expectTrue(checkDecodeUTF32([ 0x0001d800 ], [], [ 0x0001_d800 ]))


  // U+E0000 (unassigned)
  expectTrue(checkDecodeUTF32([ 0x000e0000 ], [], [ 0x000e_0000 ]))

  // U+E0100 VARIATION SELECTOR-17
  expectTrue(checkDecodeUTF32([ 0x000e0100 ], [], [ 0x000e_0100 ]))

  // U+E03FF (unassigned)
  expectTrue(checkDecodeUTF32([ 0x000e03ff ], [], [ 0x000e_03ff ]))


  // U+10FC00 (private use)
  expectTrue(checkDecodeUTF32([ 0x0010fc00 ], [], [ 0x0010_fc00 ]))

  // U+10FD00 (private use)
  expectTrue(checkDecodeUTF32([ 0x0010fd00 ], [], [ 0x0010_fd00 ]))

  // U+10FFFF (private use, noncharacter)
  expectTrue(checkDecodeUTF32([ 0x0010ffff ], [], [ 0x0010_ffff ]))
}

UTF32Decoder.test("IllFormed") {
  // U+D800 (high-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_d800 ]))

  // U+DB40 (high-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_db40 ]))

  // U+DBFF (high-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_dbff ]))

  // U+DC00 (low-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_dc00 ]))

  // U+DD00 (low-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_dd00 ]))

  // U+DFFF (low-surrogate)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0000_dfff ]))

  // U+110000 (invalid)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0011_0000 ]))

  // U+1000000 (invalid)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x0100_0000 ]))

  // U+80000000 (invalid)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0x8000_0000 ]))

  // U+FFFF0000 (invalid)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0xffff_0000 ]))

  // U+FFFFFFFF (invalid)
  expectTrue(checkDecodeUTF32([], [ 0xfffd ], [ 0xffff_ffff ]))
}

var UTF8Decoder = TestSuite("UTF8Decoder")

//===----------------------------------------------------------------------===//
public struct UTFTest {
  public struct Flags : OptionSet {
    public let rawValue: Int

    public init(rawValue: Int) {
      self.rawValue = rawValue
    }

    public static let utf8IsInvalid = Flags(rawValue: 1 << 0)
    public static let utf16IsInvalid = Flags(rawValue: 1 << 1)
  }

  public let string: String
  public let utf8: [UInt8]
  public let utf16: [UInt16]
  public let unicodeScalars: [Unicode.Scalar]
  public let unicodeScalarsRepairedTail: [Unicode.Scalar]
  public let flags: Flags
  public let loc: SourceLoc

  public var utf32: [UInt32] {
    return unicodeScalars.map(UInt32.init)
  }

  public var utf32RepairedTail: [UInt32] {
    return unicodeScalarsRepairedTail.map(UInt32.init)
  }

  public init(
    string: String,
    utf8: [UInt8],
    utf16: [UInt16],
    scalars: [UInt32],
    scalarsRepairedTail: [UInt32] = [],
    flags: Flags = [],
    file: String = #file, line: UInt = #line
  ) {
    self.string = string
    self.utf8 = utf8
    self.utf16 = utf16
    self.unicodeScalars = scalars.map { Unicode.Scalar($0)! }
    self.unicodeScalarsRepairedTail =
      scalarsRepairedTail.map { Unicode.Scalar($0)! }
    self.flags = flags
    self.loc = SourceLoc(file, line, comment: "test data")
  }
}

public var utfTests: [UTFTest] = []
  //
  // Empty sequence.
  //

utfTests.append(
  UTFTest(
    string: "",
    utf8: [],
    utf16: [],
    scalars: []))

  //
  // 1-byte sequences.
  //

  // U+0000 NULL
utfTests.append(
  UTFTest(
    string: "\u{0000}",
    utf8: [ 0x00 ],
    utf16: [ 0x00 ],
    scalars: [ 0x00 ]))

  // U+0041 LATIN CAPITAL LETTER A
utfTests.append(
  UTFTest(
    string: "A",
    utf8: [ 0x41 ],
    utf16: [ 0x41 ],
    scalars: [ 0x41 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
utfTests.append(
  UTFTest(
    string: "AB",
    utf8: [ 0x41, 0x42 ],
    utf16: [ 0x41, 0x42 ],
    scalars: [ 0x41, 0x42 ]))

  // U+0061 LATIN SMALL LETTER A
  // U+0062 LATIN SMALL LETTER B
  // U+0063 LATIN SMALL LETTER C
utfTests.append(
  UTFTest(
    string: "ABC",
    utf8: [ 0x41, 0x42, 0x43 ],
    utf16: [ 0x41, 0x42, 0x43 ],
    scalars: [ 0x41, 0x42, 0x43 ]))

  // U+0000 NULL
  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0000 NULL
utfTests.append(
  UTFTest(
    string: "\u{0000}AB\u{0000}",
    utf8: [ 0x00, 0x41, 0x42, 0x00 ],
    utf16: [ 0x00, 0x41, 0x42, 0x00 ],
    scalars: [ 0x00, 0x41, 0x42, 0x00 ]))

  // U+007F DELETE
utfTests.append(
  UTFTest(
    string: "\u{007F}",
    utf8: [ 0x7F ],
    utf16: [ 0x7F ],
    scalars: [ 0x7F ]))

  //
  // 2-byte sequences.
  //

  // U+0283 LATIN SMALL LETTER ESH
utfTests.append(
  UTFTest(
    string: "\u{0283}",
    utf8: [ 0xCA, 0x83 ],
    utf16: [ 0x0283 ],
    scalars: [ 0x0283 ]))

  // U+03BA GREEK SMALL LETTER KAPPA
  // U+1F79 GREEK SMALL LETTER OMICRON WITH OXIA
  // U+03C3 GREEK SMALL LETTER SIGMA
  // U+03BC GREEK SMALL LETTER MU
  // U+03B5 GREEK SMALL LETTER EPSILON
utfTests.append(
  UTFTest(
    string: "\u{03BA}\u{1F79}\u{03C3}\u{03BC}\u{03B5}",
    utf8: [ 0xCE, 0xBA, 0xE1, 0xBD, 0xB9, 0xCF, 0x83, 0xCE, 0xBC, 0xCE, 0xB5 ],
    utf16: [ 0x03BA, 0x1F79, 0x03C3, 0x03BC, 0x03B5 ],
    scalars: [ 0x03BA, 0x1F79, 0x03C3, 0x03BC, 0x03B5 ]))

  // U+0430 CYRILLIC SMALL LETTER A
  // U+0431 CYRILLIC SMALL LETTER BE
  // U+0432 CYRILLIC SMALL LETTER VE
utfTests.append(
  UTFTest(
    string: "\u{0430}\u{0431}\u{0432}",
    utf8: [ 0xD0, 0xB0, 0xD0, 0xB1, 0xD0, 0xB2 ],
    utf16: [ 0x0430, 0x0431, 0x0432 ],
    scalars: [ 0x0430, 0x0431, 0x0432 ]))

  //
  // 3-byte sequences.
  //

  // U+4F8B CJK UNIFIED IDEOGRAPH-4F8B
  // U+6587 CJK UNIFIED IDEOGRAPH-6587
utfTests.append(
  UTFTest(
    string: "\u{4F8b}\u{6587}",
    utf8: [ 0xE4, 0xBE, 0x8B, 0xE6, 0x96, 0x87 ],
    utf16: [ 0x4F8B, 0x6587 ],
    scalars: [ 0x4F8B, 0x6587 ]))

  // U+D55C HANGUL SYLLABLE HAN
  // U+AE00 HANGUL SYLLABLE GEUL
utfTests.append(
  UTFTest(
    string: "\u{d55c}\u{ae00}",
    utf8: [ 0xED, 0x95, 0x9C, 0xEA, 0xB8, 0x80 ],
    utf16: [ 0xD55C, 0xAE00 ],
    scalars: [ 0xD55C, 0xAE00 ]))

  // U+1112 HANGUL CHOSEONG HIEUH
  // U+1161 HANGUL JUNGSEONG A
  // U+11AB HANGUL JONGSEONG NIEUN
  // U+1100 HANGUL CHOSEONG KIYEOK
  // U+1173 HANGUL JUNGSEONG EU
  // U+11AF HANGUL JONGSEONG RIEUL
utfTests.append(
  UTFTest(
    string: "\u{1112}\u{1161}\u{11ab}\u{1100}\u{1173}\u{11af}",
    utf8:
      [ 0xE1, 0x84, 0x92, 0xE1, 0x85, 0xA1, 0xE1, 0x86, 0xAB,
        0xE1, 0x84, 0x80, 0xE1, 0x85, 0xB3, 0xE1, 0x86, 0xAF ],
    utf16: [ 0x1112, 0x1161, 0x11AB, 0x1100, 0x1173, 0x11AF ],
    scalars: [ 0x1112, 0x1161, 0x11AB, 0x1100, 0x1173, 0x11AF ]))

  // U+3042 HIRAGANA LETTER A
  // U+3044 HIRAGANA LETTER I
  // U+3046 HIRAGANA LETTER U
  // U+3048 HIRAGANA LETTER E
  // U+304A HIRAGANA LETTER O
utfTests.append(
  UTFTest(
    string: "\u{3042}\u{3044}\u{3046}\u{3048}\u{304a}",
    utf8:
      [ 0xE3, 0x81, 0x82, 0xE3, 0x81, 0x84, 0xE3, 0x81, 0x86,
        0xE3, 0x81, 0x88, 0xE3, 0x81, 0x8A ],
    utf16: [ 0x3042, 0x3044, 0x3046, 0x3048, 0x304A ],
    scalars: [ 0x3042, 0x3044, 0x3046, 0x3048, 0x304A ]))

  // U+D7FF (unassigned)
utfTests.append(
  UTFTest(
    string: "\u{D7FF}",
    utf8: [ 0xED, 0x9F, 0xBF ],
    utf16: [ 0xD7FF ],
    scalars: [ 0xD7FF ]))

  // U+E000 (private use)
utfTests.append(
  UTFTest(
    string: "\u{E000}",
    utf8: [ 0xEE, 0x80, 0x80 ],
    utf16: [ 0xE000 ],
    scalars: [ 0xE000 ]))

  // U+FFFD REPLACEMENT CHARACTER
utfTests.append(
  UTFTest(
    string: "\u{FFFD}",
    utf8: [ 0xEF, 0xBF, 0xBD ],
    utf16: [ 0xFFFD ],
    scalars: [ 0xFFFD ]))

  // U+FFFF (noncharacter)
utfTests.append(
  UTFTest(
    string: "\u{FFFF}",
    utf8: [ 0xEF, 0xBF, 0xBF ],
    utf16: [ 0xFFFF ],
    scalars: [ 0xFFFF ]))

  //
  // 4-byte sequences.
  //

  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "\u{1F425}",
    utf8: [ 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0xD83D, 0xDC25 ],
    scalars: [ 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "A\u{1F425}",
    utf8: [ 0x41, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "AB\u{1F425}",
    utf8: [ 0x41, 0x42, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABC\u{1F425}",
    utf8: [ 0x41, 0x42, 0x43, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0x43, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x43, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCD\u{1F425}",
    utf8: [ 0x41, 0x42, 0x43, 0x44, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0x43, 0x44, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x43, 0x44, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+0045 LATIN CAPITAL LETTER E
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCDE\u{1F425}",
    utf8: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+0045 LATIN CAPITAL LETTER E
  // U+0046 LATIN CAPITAL LETTER F
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCDEF\u{1F425}",
    utf8: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+0045 LATIN CAPITAL LETTER E
  // U+0046 LATIN CAPITAL LETTER F
  // U+0047 LATIN CAPITAL LETTER G
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCDEFG\u{1F425}",
    utf8: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0xF0, 0x9F, 0x90, 0xA5 ],
    utf16: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0xD83D, 0xDC25 ],
    scalars: [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+0045 LATIN CAPITAL LETTER E
  // U+0046 LATIN CAPITAL LETTER F
  // U+0047 LATIN CAPITAL LETTER G
  // U+0048 LATIN CAPITAL LETTER H
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCDEFGH\u{1F425}",
    utf8:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
        0xF0, 0x9F, 0x90, 0xA5 ],
    utf16:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
        0xD83D, 0xDC25 ],
    scalars:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x0001_F425 ]))

  // U+0041 LATIN CAPITAL LETTER A
  // U+0042 LATIN CAPITAL LETTER B
  // U+0043 LATIN CAPITAL LETTER C
  // U+0044 LATIN CAPITAL LETTER D
  // U+0045 LATIN CAPITAL LETTER E
  // U+0046 LATIN CAPITAL LETTER F
  // U+0047 LATIN CAPITAL LETTER G
  // U+0048 LATIN CAPITAL LETTER H
  // U+0049 LATIN CAPITAL LETTER I
  // U+1F425 FRONT-FACING BABY CHICK
utfTests.append(
  UTFTest(
    string: "ABCDEFGHI\u{1F425}",
    utf8:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
        0xF0, 0x9F, 0x90, 0xA5 ],
    utf16:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
        0xD83D, 0xDC25 ],
    scalars:
      [ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x0001_F425 ]))

  // U+10000 LINEAR B SYLLABLE B008 A
utfTests.append(
  UTFTest(
    string: "\u{10000}",
    utf8: [ 0xF0, 0x90, 0x80, 0x80 ],
    utf16: [ 0xD800, 0xDC00 ],
    scalars: [ 0x0001_0000 ]))

  // U+10100 AEGEAN WORD SEPARATOR LINE
utfTests.append(
  UTFTest(
    string: "\u{10100}",
    utf8: [ 0xF0, 0x90, 0x84, 0x80 ],
    utf16: [ 0xD800, 0xDD00 ],
    scalars: [ 0x0001_0100 ]))

  // U+103FF (unassigned)
utfTests.append(
  UTFTest(
    string: "\u{103FF}",
    utf8: [ 0xF0, 0x90, 0x8F, 0xBF ],
    utf16: [ 0xD800, 0xDFFF ],
    scalars: [ 0x0001_03FF ]))

  // U+E0000 (unassigned)
utfTests.append(
  UTFTest(
    string: "\u{E0000}",
    utf8: [ 0xF3, 0xA0, 0x80, 0x80 ],
    utf16: [ 0xDB40, 0xDC00 ],
    scalars: [ 0x000E_0000 ]))

  // U+E0100 VARIATION SELECTOR-17
utfTests.append(
  UTFTest(
    string: "\u{E0100}",
    utf8: [ 0xF3, 0xA0, 0x84, 0x80 ],
    utf16: [ 0xDB40, 0xDD00 ],
    scalars: [ 0x000E_0100 ]))

  // U+E03FF (unassigned)
utfTests.append(
  UTFTest(
    string: "\u{E03FF}",
    utf8: [ 0xF3, 0xA0, 0x8F, 0xBF ],
    utf16: [ 0xDB40, 0xDFFF ],
    scalars: [ 0x000E_03FF ]))

  // U+10FC00 (private use)
utfTests.append(
  UTFTest(
    string: "\u{10FC00}",
    utf8: [ 0xF4, 0x8F, 0xB0, 0x80 ],
    utf16: [ 0xDBFF, 0xDC00 ],
    scalars: [ 0x0010_FC00 ]))

  // U+10FD00 (private use)
utfTests.append(
  UTFTest(
    string: "\u{10FD00}",
    utf8: [ 0xF4, 0x8F, 0xB4, 0x80 ],
    utf16: [ 0xDBFF, 0xDD00 ],
    scalars: [ 0x0010_FD00 ]))

  // U+10FFFF (private use, noncharacter)
utfTests.append(
  UTFTest(
    string: "\u{10FFFF}",
    utf8: [ 0xF4, 0x8F, 0xBF, 0xBF ],
    utf16: [ 0xDBFF, 0xDFFF ],
    scalars: [ 0x0010_FFFF ]))
//===----------------------------------------------------------------------===//

UTF8Decoder.test("SmokeTest").forEach(in: utfTests) {
  test in

  expectTrue(
    checkDecodeUTF8(test.utf32, [], test.utf8),
    stackTrace: test.loc.withCurrentLoc())
  return ()
}

UTF8Decoder.test("FirstPossibleSequence") {
  //
  // First possible sequence of a certain length
  //

  // U+0000 NULL
  expectTrue(checkDecodeUTF8([ 0x0000 ], [], [ 0x00 ]))

  // U+0080 PADDING CHARACTER
  expectTrue(checkDecodeUTF8([ 0x0080 ], [], [ 0xc2, 0x80 ]))

  // U+0800 SAMARITAN LETTER ALAF
  expectTrue(checkDecodeUTF8(
      [ 0x0800 ], [],
      [ 0xe0, 0xa0, 0x80 ]))

  // U+10000 LINEAR B SYLLABLE B008 A
  expectTrue(checkDecodeUTF8(
      [ 0x10000 ], [],
      [ 0xf0, 0x90, 0x80, 0x80 ]))

  // U+200000 (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x88, 0x80, 0x80, 0x80 ]))

  // U+4000000 (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x84, 0x80, 0x80, 0x80, 0x80 ]))
}

UTF8Decoder.test("LastPossibleSequence") {
  //
  // Last possible sequence of a certain length
  //

  // U+007F DELETE
  expectTrue(checkDecodeUTF8([ 0x007f ], [], [ 0x7f ]))

  // U+07FF (unassigned)
  expectTrue(checkDecodeUTF8([ 0x07ff ], [], [ 0xdf, 0xbf ]))

  // U+FFFF (noncharacter)
  expectTrue(checkDecodeUTF8(
      [ 0xffff ], [],
      [ 0xef, 0xbf, 0xbf ]))

  // U+1FFFFF (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf7, 0xbf, 0xbf, 0xbf ]))

  // U+3FFFFFF (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfb, 0xbf, 0xbf, 0xbf, 0xbf ]))

  // U+7FFFFFFF (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf ]))
}

UTF8Decoder.test("CodeSpaceBoundaryConditions") {
  //
  // Other boundary conditions
  //

  // U+D7FF (unassigned)
  expectTrue(checkDecodeUTF8([ 0xd7ff ], [], [ 0xed, 0x9f, 0xbf ]))

  // U+E000 (private use)
  expectTrue(checkDecodeUTF8([ 0xe000 ], [], [ 0xee, 0x80, 0x80 ]))

  // U+FFFD REPLACEMENT CHARACTER
  expectTrue(checkDecodeUTF8([ 0xfffd ], [], [ 0xef, 0xbf, 0xbd ]))

  // U+10FFFF (noncharacter)
  expectTrue(checkDecodeUTF8([ 0x10ffff ], [], [ 0xf4, 0x8f, 0xbf, 0xbf ]))
  
  // U+110000 (invalid)
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf4, 0x90, 0x80, 0x80 ]))
}

UTF8Decoder.test("UnexpectedContinuationBytes") {
  //
  // Unexpected continuation bytes
  //

  // A sequence of unexpected continuation bytes that don't follow a first
  // byte, every byte is a maximal subpart.

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0x80, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xbf, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0x80, 0xbf, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0x80, 0xbf, 0x80, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0x80, 0xbf, 0x82, 0xbf, 0xaa ]))
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xaa, 0xb0, 0xbb, 0xbf, 0xaa, 0xa0 ]))
  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xaa, 0xb0, 0xbb, 0xbf, 0xaa, 0xa0, 0x8f ]))

  // All continuation bytes (0x80--0xbf).
  expectTrue(checkDecodeUTF8(
      [],
      [ 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 ],
      [ 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 ]))
}

UTF8Decoder.test("LonelyStartBytes") {
  //
  // Lonely start bytes
  //

  // Start bytes of 2-byte sequences (0xc0--0xdf).
  expectTrue(checkDecodeUTF8(
      [],
      [ 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 ],
      [ 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
        0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
        0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
        0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 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 ]))

  // Start bytes of 3-byte sequences (0xe0--0xef).
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd,
        0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
        0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 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 ]))

  // Start bytes of 4-byte sequences (0xf0--0xf7).
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7 ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020,
        0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 0xf0, 0x20, 0xf1, 0x20, 0xf2, 0x20, 0xf3, 0x20,
        0xf4, 0x20, 0xf5, 0x20, 0xf6, 0x20, 0xf7, 0x20 ]))

  // Start bytes of 5-byte sequences (0xf8--0xfb).
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0xf9, 0xfa, 0xfb ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 0xf8, 0x20, 0xf9, 0x20, 0xfa, 0x20, 0xfb, 0x20 ]))

  // Start bytes of 6-byte sequences (0xfc--0xfd).
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfc, 0xfd ]))

  expectTrue(checkDecodeUTF8(
      [], [ 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 0xfc, 0x20, 0xfd, 0x20 ]))
}

UTF8Decoder.test("InvalidStartBytes") {
  //
  // Other bytes (0xc0--0xc1, 0xfe--0xff).
  //

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xc0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xc1 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfe ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xff ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xc0, 0xc1, 0xfe, 0xff ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfe, 0xfe, 0xff, 0xff ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfe, 0x80, 0x80, 0x80, 0x80, 0x80 ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xff, 0x80, 0x80, 0x80, 0x80, 0x80 ]))

  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020, 0xfffd, 0x0020 ],
      [ 0xc0, 0x20, 0xc1, 0x20, 0xfe, 0x20, 0xff, 0x20 ]))
}

UTF8Decoder.test("MissingContinuationBytes") {
  //
  // Sequences with one continuation byte missing
  //

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xc2 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xdf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xc2, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xdf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xe0, 0xa0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xe0, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xe0, 0xa0, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xe0, 0xbf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xe1, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xec, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xe1, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xec, 0xbf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xed, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xed, 0x9f ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xed, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xed, 0x9f, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xee, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xef, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xee, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xef, 0xbf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0, 0x90, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf0, 0x90, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf0, 0xbf, 0xbf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf1, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf3, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf1, 0x80, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf3, 0xbf, 0xbf, 0x41 ]))

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf4, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf4, 0x8f, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf4, 0x80, 0x80, 0x41 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0x0041 ], [ 0xf4, 0x8f, 0xbf, 0x41 ]))

  // Overlong sequences with one trailing byte missing.
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xc0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xc1 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xe0, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xe0, 0x9f ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x8f, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x80, 0x80, 0x80, 0x80 ]))

  // Sequences that represent surrogates with one trailing byte missing.
  // High-surrogates
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xa0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xac ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xaf ]))
  // Low-surrogates
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xb0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xb4 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xed, 0xbf ]))

  // Ill-formed 4-byte sequences.
  // 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+1100xx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf4, 0x90, 0x80 ]))
  // U+13FBxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf4, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf5, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf6, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf7, 0x80, 0x80 ]))
  // U+1FFBxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf7, 0xbf, 0xbf ]))

  // Ill-formed 5-byte sequences.
  // 111110uu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+2000xx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x88, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0xbf, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf9, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfa, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfb, 0x80, 0x80, 0x80 ]))
  // U+3FFFFxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfb, 0xbf, 0xbf, 0xbf ]))

  // Ill-formed 6-byte sequences.
  // 1111110u 10uuuuuu 10uzzzzz 10zzzyyyy 10yyyyxx 10xxxxxx
  // U+40000xx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x84, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0xbf, 0xbf, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0x80, 0x80, 0x80, 0x80 ]))
  // U+7FFFFFxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0xbf, 0xbf, 0xbf, 0xbf ]))

  //
  // Sequences with two continuation bytes missing
  //

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0, 0x90 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf1, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf3, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf4, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf4, 0x8f ]))

  // Overlong sequences with two trailing byte missing.
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xe0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf0, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf0, 0x8f ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x80, 0x80, 0x80 ]))

  // Sequences that represent surrogates with two trailing bytes missing.
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xed ]))

  // Ill-formed 4-byte sequences.
  // 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+110yxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf4, 0x90 ]))
  // U+13Fyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf4, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf5, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf6, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf7, 0x80 ]))
  // U+1FFyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf7, 0xbf ]))

  // Ill-formed 5-byte sequences.
  // 111110uu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+200yxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x88, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf9, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfa, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfb, 0x80, 0x80 ]))
  // U+3FFFyxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfb, 0xbf, 0xbf ]))

  // Ill-formed 6-byte sequences.
  // 1111110u 10uuuuuu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+4000yxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x84, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0xbf, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0x80, 0x80, 0x80 ]))
  // U+7FFFFyxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0xbf, 0xbf, 0xbf ]))

  //
  // Sequences with three continuation bytes missing
  //

  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf1 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf2 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf3 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf4 ]))

  // Broken overlong sequences.
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf0 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf8, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x80, 0x80 ]))

  // Ill-formed 4-byte sequences.
  // 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+14yyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf5 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf6 ]))
  // U+1Cyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf7 ]))

  // Ill-formed 5-byte sequences.
  // 111110uu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+20yyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf8, 0x88 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf8, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xf9, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfa, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfb, 0x80 ]))
  // U+3FCyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfb, 0xbf ]))

  // Ill-formed 6-byte sequences.
  // 1111110u 10uuuuuu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+400yyxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x84, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0x80, 0x80 ]))
  // U+7FFCyyxx (invalid)
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfd, 0xbf, 0xbf ]))

  //
  // Sequences with four continuation bytes missing
  //

  // Ill-formed 5-byte sequences.
  // 111110uu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+uzyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf8 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf9 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfa ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfb ]))
  // U+3zyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfb ]))

  // Broken overlong sequences.
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xf8 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfc, 0x80 ]))

  // Ill-formed 6-byte sequences.
  // 1111110u 10uuuuuu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+uzzyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfc, 0x84 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfc, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfd, 0x80 ]))
  // U+7Fzzyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xfd, 0xbf ]))

  //
  // Sequences with five continuation bytes missing
  //

  // Ill-formed 6-byte sequences.
  // 1111110u 10uuuuuu 10zzzzzz 10zzyyyy 10yyyyxx 10xxxxxx
  // U+uzzyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfc ]))
  // U+uuzzyyxx (invalid)
  expectTrue(checkDecodeUTF8([], [ 0xfffd ], [ 0xfd ]))

  //
  // Consecutive sequences with trailing bytes missing
  //

  expectTrue(checkDecodeUTF8(
      [],
      [ 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 ],
      [ 0xc0, /**/ 0xe0, 0x80, /**/ 0xf0, 0x80, 0x80,
        0xf8, 0x80, 0x80, 0x80,
        0xfc, 0x80, 0x80, 0x80, 0x80,
        0xdf, /**/ 0xef, 0xbf, /**/ 0xf7, 0xbf, 0xbf,
        0xfb, 0xbf, 0xbf, 0xbf,
        0xfd, 0xbf, 0xbf, 0xbf, 0xbf ]))
}

UTF8Decoder.test("OverlongSequences") {
  //
  // Overlong UTF-8 sequences
  //

  // U+002F SOLIDUS
  expectTrue(checkDecodeUTF8([ 0x002f ], [], [ 0x2f ]))

  // Overlong sequences of the above.
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xc0, 0xaf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xe0, 0x80, 0xaf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x80, 0x80, 0xaf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x80, 0x80, 0x80, 0xaf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x80, 0x80, 0x80, 0x80, 0xaf ]))

  // U+0000 NULL
  expectTrue(checkDecodeUTF8([ 0x0000 ], [], [ 0x00 ]))

  // Overlong sequences of the above.
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xc0, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xe0, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x80, 0x80, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x80, 0x80, 0x80, 0x80, 0x80 ]))

  // Other overlong and ill-formed sequences.
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xc0, 0xbf ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xc1, 0x80 ]))
  expectTrue(checkDecodeUTF8([], [ 0xfffd, 0xfffd ], [ 0xc1, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xe0, 0x9f, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xa0, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x8f, 0x80, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf0, 0x8f, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xf8, 0x87, 0xbf, 0xbf, 0xbf ]))
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xfc, 0x83, 0xbf, 0xbf, 0xbf, 0xbf ]))
}

UTF8Decoder.test("IsolatedSurrogates") {
  // Unicode 6.3.0:
  //
  //    D71.  High-surrogate code point: A Unicode code point in the range
  //    U+D800 to U+DBFF.
  //
  //    D73.  Low-surrogate code point: A Unicode code point in the range
  //    U+DC00 to U+DFFF.

  // Note: U+E0100 is <DB40 DD00> in UTF-16.

  // High-surrogates

  // U+D800
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xa0, 0x80 ]))
  expectTrue(checkDecodeUTF8(
      [ 0x0041 ],
      [ 0xfffd, 0xfffd, 0xfffd, 0x0041 ],
      [ 0x41, 0xed, 0xa0, 0x80, 0x41 ]))

  // U+DB40
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xac, 0xa0 ]))

  // U+DBFF
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xaf, 0xbf ]))

  // Low-surrogates

  // U+DC00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xb0, 0x80 ]))

  // U+DD00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xb4, 0x80 ]))

  // U+DFFF
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xbf, 0xbf ]))
}

UTF8Decoder.test("SurrogatePairs") {
  // Surrogate pairs

  // U+D800 U+DC00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xa0, 0x80, 0xed, 0xb0, 0x80 ]))

  // U+D800 U+DD00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xa0, 0x80, 0xed, 0xb4, 0x80 ]))

  // U+D800 U+DFFF
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xa0, 0x80, 0xed, 0xbf, 0xbf ]))

  // U+DB40 U+DC00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xac, 0xa0, 0xed, 0xb0, 0x80 ]))

  // U+DB40 U+DD00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xac, 0xa0, 0xed, 0xb4, 0x80 ]))

  // U+DB40 U+DFFF
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xac, 0xa0, 0xed, 0xbf, 0xbf ]))

  // U+DBFF U+DC00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xaf, 0xbf, 0xed, 0xb0, 0x80 ]))

  // U+DBFF U+DD00
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xaf, 0xbf, 0xed, 0xb4, 0x80 ]))

  // U+DBFF U+DFFF
  expectTrue(checkDecodeUTF8(
      [],
      [ 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd, 0xfffd ],
      [ 0xed, 0xaf, 0xbf, 0xed, 0xbf, 0xbf ]))
}

UTF8Decoder.test("Noncharacters") {
  //
  // Noncharacters
  //

  // Unicode 6.3.0:
  //
  //    D14.  Noncharacter: A code point that is permanently reserved for
  //    internal use and that should never be interchanged. Noncharacters
  //    consist of the values U+nFFFE and U+nFFFF (where n is from 0 to 1016)
  //    and the values U+FDD0..U+FDEF.

  // U+FFFE
  expectTrue(checkDecodeUTF8([ 0xfffe ], [], [ 0xef, 0xbf, 0xbe ]))

  // U+FFFF
  expectTrue(checkDecodeUTF8([ 0xffff ], [], [ 0xef, 0xbf, 0xbf ]))

  // U+1FFFE
  expectTrue(checkDecodeUTF8([ 0x1fffe ], [], [ 0xf0, 0x9f, 0xbf, 0xbe ]))

  // U+1FFFF
  expectTrue(checkDecodeUTF8([ 0x1ffff ], [], [ 0xf0, 0x9f, 0xbf, 0xbf ]))

  // U+2FFFE
  expectTrue(checkDecodeUTF8([ 0x2fffe ], [], [ 0xf0, 0xaf, 0xbf, 0xbe ]))

  // U+2FFFF
  expectTrue(checkDecodeUTF8([ 0x2ffff ], [], [ 0xf0, 0xaf, 0xbf, 0xbf ]))

  // U+3FFFE
  expectTrue(checkDecodeUTF8([ 0x3fffe ], [], [ 0xf0, 0xbf, 0xbf, 0xbe ]))

  // U+3FFFF
  expectTrue(checkDecodeUTF8([ 0x3ffff ], [], [ 0xf0, 0xbf, 0xbf, 0xbf ]))

  // U+4FFFE
  expectTrue(checkDecodeUTF8([ 0x4fffe ], [], [ 0xf1, 0x8f, 0xbf, 0xbe ]))

  // U+4FFFF
  expectTrue(checkDecodeUTF8([ 0x4ffff ], [], [ 0xf1, 0x8f, 0xbf, 0xbf ]))

  // U+5FFFE
  expectTrue(checkDecodeUTF8([ 0x5fffe ], [], [ 0xf1, 0x9f, 0xbf, 0xbe ]))

  // U+5FFFF
  expectTrue(checkDecodeUTF8([ 0x5ffff ], [], [ 0xf1, 0x9f, 0xbf, 0xbf ]))

  // U+6FFFE
  expectTrue(checkDecodeUTF8([ 0x6fffe ], [], [ 0xf1, 0xaf, 0xbf, 0xbe ]))

  // U+6FFFF
  expectTrue(checkDecodeUTF8([ 0x6ffff ], [], [ 0xf1, 0xaf, 0xbf, 0xbf ]))

  // U+7FFFE
  expectTrue(checkDecodeUTF8([ 0x7fffe ], [], [ 0xf1, 0xbf, 0xbf, 0xbe ]))

  // U+7FFFF
  expectTrue(checkDecodeUTF8([ 0x7ffff ], [], [ 0xf1, 0xbf, 0xbf, 0xbf ]))

  // U+8FFFE
  expectTrue(checkDecodeUTF8([ 0x8fffe ], [], [ 0xf2, 0x8f, 0xbf, 0xbe ]))

  // U+8FFFF
  expectTrue(checkDecodeUTF8([ 0x8ffff ], [], [ 0xf2, 0x8f, 0xbf, 0xbf ]))

  // U+9FFFE
  expectTrue(checkDecodeUTF8([ 0x9fffe ], [], [ 0xf2, 0x9f, 0xbf, 0xbe ]))

  // U+9FFFF
  expectTrue(checkDecodeUTF8([ 0x9ffff ], [], [ 0xf2, 0x9f, 0xbf, 0xbf ]))

  // U+AFFFE
  expectTrue(checkDecodeUTF8([ 0xafffe ], [], [ 0xf2, 0xaf, 0xbf, 0xbe ]))

  // U+AFFFF
  expectTrue(checkDecodeUTF8([ 0xaffff ], [], [ 0xf2, 0xaf, 0xbf, 0xbf ]))

  // U+BFFFE
  expectTrue(checkDecodeUTF8([ 0xbfffe ], [], [ 0xf2, 0xbf, 0xbf, 0xbe ]))

  // U+BFFFF
  expectTrue(checkDecodeUTF8([ 0xbffff ], [], [ 0xf2, 0xbf, 0xbf, 0xbf ]))

  // U+CFFFE
  expectTrue(checkDecodeUTF8([ 0xcfffe ], [], [ 0xf3, 0x8f, 0xbf, 0xbe ]))

  // U+CFFFF
  expectTrue(checkDecodeUTF8([ 0xcfffF ], [], [ 0xf3, 0x8f, 0xbf, 0xbf ]))

  // U+DFFFE
  expectTrue(checkDecodeUTF8([ 0xdfffe ], [], [ 0xf3, 0x9f, 0xbf, 0xbe ]))

  // U+DFFFF
  expectTrue(checkDecodeUTF8([ 0xdffff ], [], [ 0xf3, 0x9f, 0xbf, 0xbf ]))

  // U+EFFFE
  expectTrue(checkDecodeUTF8([ 0xefffe ], [], [ 0xf3, 0xaf, 0xbf, 0xbe ]))

  // U+EFFFF
  expectTrue(checkDecodeUTF8([ 0xeffff ], [], [ 0xf3, 0xaf, 0xbf, 0xbf ]))

  // U+FFFFE
  expectTrue(checkDecodeUTF8([ 0xffffe ], [], [ 0xf3, 0xbf, 0xbf, 0xbe ]))

  // U+FFFFF
  expectTrue(checkDecodeUTF8([ 0xfffff ], [], [ 0xf3, 0xbf, 0xbf, 0xbf ]))

  // U+10FFFE
  expectTrue(checkDecodeUTF8([ 0x10fffe ], [], [ 0xf4, 0x8f, 0xbf, 0xbe ]))

  // U+10FFFF
  expectTrue(checkDecodeUTF8([ 0x10ffff ], [], [ 0xf4, 0x8f, 0xbf, 0xbf ]))

  // U+FDD0
  expectTrue(checkDecodeUTF8([ 0xfdd0 ], [], [ 0xef, 0xb7, 0x90 ]))

  // U+FDD1
  expectTrue(checkDecodeUTF8([ 0xfdd1 ], [], [ 0xef, 0xb7, 0x91 ]))

  // U+FDD2
  expectTrue(checkDecodeUTF8([ 0xfdd2 ], [], [ 0xef, 0xb7, 0x92 ]))

  // U+FDD3
  expectTrue(checkDecodeUTF8([ 0xfdd3 ], [], [ 0xef, 0xb7, 0x93 ]))

  // U+FDD4
  expectTrue(checkDecodeUTF8([ 0xfdd4 ], [], [ 0xef, 0xb7, 0x94 ]))

  // U+FDD5
  expectTrue(checkDecodeUTF8([ 0xfdd5 ], [], [ 0xef, 0xb7, 0x95 ]))

  // U+FDD6
  expectTrue(checkDecodeUTF8([ 0xfdd6 ], [], [ 0xef, 0xb7, 0x96 ]))

  // U+FDD7
  expectTrue(checkDecodeUTF8([ 0xfdd7 ], [], [ 0xef, 0xb7, 0x97 ]))

  // U+FDD8
  expectTrue(checkDecodeUTF8([ 0xfdd8 ], [], [ 0xef, 0xb7, 0x98 ]))

  // U+FDD9
  expectTrue(checkDecodeUTF8([ 0xfdd9 ], [], [ 0xef, 0xb7, 0x99 ]))

  // U+FDDA
  expectTrue(checkDecodeUTF8([ 0xfdda ], [], [ 0xef, 0xb7, 0x9a ]))

  // U+FDDB
  expectTrue(checkDecodeUTF8([ 0xfddb ], [], [ 0xef, 0xb7, 0x9b ]))

  // U+FDDC
  expectTrue(checkDecodeUTF8([ 0xfddc ], [], [ 0xef, 0xb7, 0x9c ]))

  // U+FDDD
  expectTrue(checkDecodeUTF8([ 0xfddd ], [], [ 0xef, 0xb7, 0x9d ]))

  // U+FDDE
  expectTrue(checkDecodeUTF8([ 0xfdde ], [], [ 0xef, 0xb7, 0x9e ]))

  // U+FDDF
  expectTrue(checkDecodeUTF8([ 0xfddf ], [], [ 0xef, 0xb7, 0x9f ]))

  // U+FDE0
  expectTrue(checkDecodeUTF8([ 0xfde0 ], [], [ 0xef, 0xb7, 0xa0 ]))

  // U+FDE1
  expectTrue(checkDecodeUTF8([ 0xfde1 ], [], [ 0xef, 0xb7, 0xa1 ]))

  // U+FDE2
  expectTrue(checkDecodeUTF8([ 0xfde2 ], [], [ 0xef, 0xb7, 0xa2 ]))

  // U+FDE3
  expectTrue(checkDecodeUTF8([ 0xfde3 ], [], [ 0xef, 0xb7, 0xa3 ]))

  // U+FDE4
  expectTrue(checkDecodeUTF8([ 0xfde4 ], [], [ 0xef, 0xb7, 0xa4 ]))

  // U+FDE5
  expectTrue(checkDecodeUTF8([ 0xfde5 ], [], [ 0xef, 0xb7, 0xa5 ]))

  // U+FDE6
  expectTrue(checkDecodeUTF8([ 0xfde6 ], [], [ 0xef, 0xb7, 0xa6 ]))

  // U+FDE7
  expectTrue(checkDecodeUTF8([ 0xfde7 ], [], [ 0xef, 0xb7, 0xa7 ]))

  // U+FDE8
  expectTrue(checkDecodeUTF8([ 0xfde8 ], [], [ 0xef, 0xb7, 0xa8 ]))

  // U+FDE9
  expectTrue(checkDecodeUTF8([ 0xfde9 ], [], [ 0xef, 0xb7, 0xa9 ]))

  // U+FDEA
  expectTrue(checkDecodeUTF8([ 0xfdea ], [], [ 0xef, 0xb7, 0xaa ]))

  // U+FDEB
  expectTrue(checkDecodeUTF8([ 0xfdeb ], [], [ 0xef, 0xb7, 0xab ]))

  // U+FDEC
  expectTrue(checkDecodeUTF8([ 0xfdec ], [], [ 0xef, 0xb7, 0xac ]))

  // U+FDED
  expectTrue(checkDecodeUTF8([ 0xfded ], [], [ 0xef, 0xb7, 0xad ]))

  // U+FDEE
  expectTrue(checkDecodeUTF8([ 0xfdee ], [], [ 0xef, 0xb7, 0xae ]))

  // U+FDEF
  expectTrue(checkDecodeUTF8([ 0xfdef ], [], [ 0xef, 0xb7, 0xaf ]))

  // U+FDF0
  expectTrue(checkDecodeUTF8([ 0xfdf0 ], [], [ 0xef, 0xb7, 0xb0 ]))

  // U+FDF1
  expectTrue(checkDecodeUTF8([ 0xfdf1 ], [], [ 0xef, 0xb7, 0xb1 ]))

  // U+FDF2
  expectTrue(checkDecodeUTF8([ 0xfdf2 ], [], [ 0xef, 0xb7, 0xb2 ]))

  // U+FDF3
  expectTrue(checkDecodeUTF8([ 0xfdf3 ], [], [ 0xef, 0xb7, 0xb3 ]))

  // U+FDF4
  expectTrue(checkDecodeUTF8([ 0xfdf4 ], [], [ 0xef, 0xb7, 0xb4 ]))

  // U+FDF5
  expectTrue(checkDecodeUTF8([ 0xfdf5 ], [], [ 0xef, 0xb7, 0xb5 ]))

  // U+FDF6
  expectTrue(checkDecodeUTF8([ 0xfdf6 ], [], [ 0xef, 0xb7, 0xb6 ]))

  // U+FDF7
  expectTrue(checkDecodeUTF8([ 0xfdf7 ], [], [ 0xef, 0xb7, 0xb7 ]))

  // U+FDF8
  expectTrue(checkDecodeUTF8([ 0xfdf8 ], [], [ 0xef, 0xb7, 0xb8 ]))

  // U+FDF9
  expectTrue(checkDecodeUTF8([ 0xfdf9 ], [], [ 0xef, 0xb7, 0xb9 ]))

  // U+FDFA
  expectTrue(checkDecodeUTF8([ 0xfdfa ], [], [ 0xef, 0xb7, 0xba ]))

  // U+FDFB
  expectTrue(checkDecodeUTF8([ 0xfdfb ], [], [ 0xef, 0xb7, 0xbb ]))

  // U+FDFC
  expectTrue(checkDecodeUTF8([ 0xfdfc ], [], [ 0xef, 0xb7, 0xbc ]))

  // U+FDFD
  expectTrue(checkDecodeUTF8([ 0xfdfd ], [], [ 0xef, 0xb7, 0xbd ]))

  // U+FDFE
  expectTrue(checkDecodeUTF8([ 0xfdfe ], [], [ 0xef, 0xb7, 0xbe ]))

  // U+FDFF
  expectTrue(checkDecodeUTF8([ 0xfdff ], [], [ 0xef, 0xb7, 0xbf ]))
}

var UTF16Decoder = TestSuite("UTF16Decoder")

UTF16Decoder.test("UTF16.transcodedLength") {
  do {
    let u8: [Unicode.UTF8.CodeUnit] = [ 0, 1, 2, 3, 4, 5 ]
    let (count, isASCII) = Unicode.UTF16.transcodedLength(
      of: u8.makeIterator(),
      decodedAs: Unicode.UTF8.self,
      repairingIllFormedSequences: false)!
    expectEqual(6, count)
    expectTrue(isASCII)
  }

  do {
    // "€" == U+20AC.
    let u8: [Unicode.UTF8.CodeUnit] = [ 0xF0, 0xA4, 0xAD, 0xA2 ]
    let (count, isASCII) = Unicode.UTF16.transcodedLength(
      of: u8.makeIterator(),
      decodedAs: Unicode.UTF8.self,
      repairingIllFormedSequences: false)!
    expectEqual(2, count)
    expectFalse(isASCII)
  }

  do {
    let u16: [Unicode.UTF16.CodeUnit] = [ 6, 7, 8, 9, 10, 11 ]
    let (count, isASCII) = Unicode.UTF16.transcodedLength(
      of: u16.makeIterator(),
      decodedAs: Unicode.UTF16.self,
      repairingIllFormedSequences: false)!
    expectEqual(6, count)
    expectTrue(isASCII)
  }
}

UTF16Decoder.test("Decoding1").forEach(in: utfTests) {
  test in

  expectTrue(
    checkDecodeUTF16(
      test.utf32, test.utf32RepairedTail, test.utf16),
    stackTrace: test.loc.withCurrentLoc())
  return ()
}

UTF16Decoder.test("Decoding2") {
  for (name, batch) in utf16Tests {
    print("Batch: \(name)")
    for test in batch {
      expectTrue(checkDecodeUTF16(test.scalarsHead, test.scalarsRepairedTail,
          test.encoded), stackTrace: test.loc.withCurrentLoc())
    }
  }
}

public struct UTF16Test {
  public let scalarsHead: [UInt32]
  public let scalarsRepairedTail: [UInt32]
  public let encoded: [UInt16]
  public let loc: SourceLoc

  public init(
    _ scalarsHead: [UInt32], _ scalarsRepairedTail: [UInt32],
    _ encoded: [UInt16],
    file: String = #file, line: UInt = #line
  ) {
    self.scalarsHead = scalarsHead
    self.scalarsRepairedTail = scalarsRepairedTail
    self.encoded = encoded
    self.loc = SourceLoc(file, line, comment: "test data")
  }
}

public let utf16Tests = [
  "Incomplete": [
    //
    // Incomplete sequences that end right before EOF.
    //

    // U+D800 (high-surrogate)
    UTF16Test([], [ 0xFFFD ], [ 0xD800 ]),

    // U+D800 (high-surrogate)
    // U+D800 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xD800, 0xD800 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    UTF16Test([ 0x0041 ], [ 0xFFFD ], [ 0x0041, 0xD800 ]),

    // U+10000 LINEAR B SYLLABLE B008 A
    // U+D800 (high-surrogate)
    UTF16Test(
        [ 0x0001_0000 ], [ 0xFFFD ],
        [ 0xD800, 0xDC00, 0xD800 ]),

    //
    // Incomplete sequences with more code units following them.
    //

    // U+D800 (high-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test([], [ 0xFFFD, 0x0041 ], [ 0xD800, 0x0041 ]),

    // U+D800 (high-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [], [ 0xFFFD, 0x0001_0000 ],
        [ 0xD800, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0x0041 ],
        [ 0x0041, 0xD800, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xD800, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+DB40 (high-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0x0041 ],
        [ 0x0041, 0xD800, 0xDB40, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+DB40 (high-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xD800, 0xDB40, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+DB40 (high-surrogate)
    // U+DBFF (high-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0xFFFD, 0x0041 ],
        [ 0x0041, 0xD800, 0xDB40, 0xDBFF, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+D800 (high-surrogate)
    // U+DB40 (high-surrogate)
    // U+DBFF (high-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xD800, 0xDB40, 0xDBFF, 0xD800, 0xDC00 ]),
  ],

  "IllFormed": [
    //
    // Low-surrogate right before EOF.
    //

    // U+DC00 (low-surrogate)
    UTF16Test([], [ 0xFFFD ], [ 0xDC00 ]),

    // U+DC00 (low-surrogate)
    // U+DC00 (low-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDC00, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    UTF16Test([ 0x0041 ], [ 0xFFFD ], [ 0x0041, 0xDC00 ]),

    // U+10000 LINEAR B SYLLABLE B008 A
    // U+DC00 (low-surrogate)
    UTF16Test(
        [ 0x0001_0000 ], [ 0xFFFD ],
        [ 0xD800, 0xDC00, 0xDC00 ]),

    //
    // Low-surrogate with more code units following it.
    //

    // U+DC00 (low-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test([], [ 0xFFFD, 0x0041 ], [ 0xDC00, 0x0041 ]),

    // U+DC00 (low-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [], [ 0xFFFD, 0x0001_0000 ],
        [ 0xDC00, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0x0041 ],
        [ 0x0041, 0xDC00, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xDC00, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+DD00 (low-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0x0041 ],
        [ 0x0041, 0xDC00, 0xDD00, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+DD00 (low-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xDC00, 0xDD00, 0xD800, 0xDC00 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+DD00 (low-surrogate)
    // U+DFFF (low-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0xFFFD, 0x0041 ],
        [ 0x0041, 0xDC00, 0xDD00, 0xDFFF, 0x0041 ]),

    // U+0041 LATIN CAPITAL LETTER A
    // U+DC00 (low-surrogate)
    // U+DD00 (low-surrogate)
    // U+DFFF (low-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [ 0x0041 ], [ 0xFFFD, 0xFFFD, 0xFFFD, 0x0001_0000 ],
        [ 0x0041, 0xDC00, 0xDD00, 0xDFFF, 0xD800, 0xDC00 ]),

    //
    // Low-surrogate followed by high-surrogate.
    //

    // U+DC00 (low-surrogate)
    // U+D800 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDC00, 0xD800 ]),

    // U+DC00 (low-surrogate)
    // U+DB40 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDC00, 0xDB40 ]),

    // U+DC00 (low-surrogate)
    // U+DBFF (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDC00, 0xDBFF ]),


    // U+DD00 (low-surrogate)
    // U+D800 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDD00, 0xD800 ]),

    // U+DD00 (low-surrogate)
    // U+DB40 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDD00, 0xDB40 ]),

    // U+DD00 (low-surrogate)
    // U+DBFF (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDD00, 0xDBFF ]),


    // U+DFFF (low-surrogate)
    // U+D800 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDFFF, 0xD800 ]),

    // U+DFFF (low-surrogate)
    // U+DB40 (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDFFF, 0xDB40 ]),

    // U+DFFF (low-surrogate)
    // U+DBFF (high-surrogate)
    UTF16Test([], [ 0xFFFD, 0xFFFD ], [ 0xDFFF, 0xDBFF ]),


    // U+DC00 (low-surrogate)
    // U+D800 (high-surrogate)
    // U+0041 LATIN CAPITAL LETTER A
    UTF16Test(
        [], [ 0xFFFD, 0xFFFD, 0x0041 ],
        [ 0xDC00, 0xD800, 0x0041 ]),

    // U+DC00 (low-surrogate)
    // U+D800 (high-surrogate)
    // U+10000 LINEAR B SYLLABLE B008 A
    UTF16Test(
        [], [ 0xFFFD, 0xFFFD, 0x10000 ],
        [ 0xDC00, 0xD800, 0xD800, 0xDC00 ]),
  ],
]

runAllTests()

#else
//===--- benchmarking -----------------------------------------------------===//

@inline(never)
public func run_UTF8Decode(_ N: Int) {
  // 1-byte sequences
  // This test case is the longest as it's the most performance sensitive.
  let ascii = "Swift is a multi-paradigm, compiled programming language created for iOS, OS X, watchOS, tvOS and Linux development by Apple Inc. Swift is designed to work with Apple's Cocoa and Cocoa Touch frameworks and the large body of existing Objective-C code written for Apple products. Swift is intended to be more resilient to erroneous code (\"safer\") than Objective-C and also more concise. It is built with the LLVM compiler framework included in Xcode 6 and later and uses the Objective-C runtime, which allows C, Objective-C, C++ and Swift code to run within a single program."
  // 2-byte sequences
  let russian = "Ру́сский язы́к один из восточнославянских языков, национальный язык русского народа."
  // 3-byte sequences
  let japanese = "日本語（にほんご、にっぽんご）は、主に日本国内や日本人同士の間で使われている言語である。"
  // 4-byte sequences
  // Most commonly emoji, which are usually mixed with other text.
  let emoji = "Panda 🐼, Dog 🐶, Cat 🐱, Mouse 🐭."

  let strings = [ascii, russian, japanese, emoji].map { Array($0.utf8) }

  func isEmpty(_ result: UnicodeDecodingResult) -> Bool {
    switch result {
    case .emptyInput:
      return true
    default:
      return false
    }
  }

  var total: UInt32 = 0
  
  for _ in 1...200*N {
    for string in strings {
#if BASELINE
      _ = transcode(
        string.makeIterator(), from: Unicode.UTF8.self, to: Unicode.UTF32.self,
        stoppingOnError: false
      ) {
        total = total &+ $0
      }
#else
  #if FORWARD
      var it = string.makeIterator()
      typealias D = Unicode.UTF8.ForwardParser
      D.decode(&it, repairingIllFormedSequences: true) { total = total &+ $0.value }
  #elseif REVERSE
      var it = string.reversed().makeIterator()
      typealias D = Unicode.UTF8.ReverseParser
      D.decode(&it, repairingIllFormedSequences: true) { total = total &+ $0.value }
  #elseif SEQUENCE
      for s in Unicode.DefaultScalarView(string, fromEncoding: Unicode.UTF8.self) {
        total = total &+ s.value
      }
  #elseif COLLECTION
      let scalars = Unicode.DefaultScalarView(string, fromEncoding: Unicode.UTF8.self)
      var i = scalars.startIndex
      while i != scalars.endIndex {
        total = total &+ scalars[i].value
        i = scalars.index(after: i)
      }
#elseif REVERSE_COLLECTION
      let scalars = Unicode.DefaultScalarView(string, fromEncoding: Unicode.UTF8.self)
      var i = scalars.endIndex
      while i != scalars.startIndex {
        i = scalars.index(before: i)
        total = total &+ scalars[i].value
      }
  #else
      Error_Unknown_Benchmark()
  #endif
#endif
    }
  }
  if CommandLine.arguments.count > 1000 { print(total) }
}

run_UTF8Decode(10000)
#endif