llvm/unittests/Support/JSONTest.cpp

   1 //===-- JSONTest.cpp - JSON unit tests --------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Support/JSON.h"
  10 #include "llvm/Support/raw_ostream.h"
  11 #include "llvm/Testing/Support/Error.h"
  12
  13 #include "gmock/gmock.h"
  14 #include "gtest/gtest.h"
  15
  16 namespace llvm {
  17 namespace json {
  18
  19 namespace {
  20
  21 std::string s(const Value &E) { return llvm::formatv("{0}", E).str(); }
  22 std::string sp(const Value &E) { return llvm::formatv("{0:2}", E).str(); }
  23
  24 TEST(JSONTest, Types) {
  25   EXPECT_EQ("true", s(true));
  26   EXPECT_EQ("null", s(nullptr));
  27   EXPECT_EQ("2.5", s(2.5));
  28   EXPECT_EQ(R"("foo")", s("foo"));
  29   EXPECT_EQ("[1,2,3]", s({1, 2, 3}));
  30   EXPECT_EQ(R"({"x":10,"y":20})", s(Object{{"x", 10}, {"y", 20}}));
  31
  32 #ifdef NDEBUG
  33   EXPECT_EQ(R"("��")", s("\xC0\x80"));
  34   EXPECT_EQ(R"({"��":0})", s(Object{{"\xC0\x80", 0}}));
  35 #else
  36   EXPECT_DEATH(s("\xC0\x80"), "Invalid UTF-8");
  37   EXPECT_DEATH(s(Object{{"\xC0\x80", 0}}), "Invalid UTF-8");
  38 #endif
  39 }
  40
  41 TEST(JSONTest, Constructors) {
  42   // Lots of edge cases around empty and singleton init lists.
  43   EXPECT_EQ("[[[3]]]", s({{{3}}}));
  44   EXPECT_EQ("[[[]]]", s({{{}}}));
  45   EXPECT_EQ("[[{}]]", s({{Object{}}}));
  46   EXPECT_EQ(R"({"A":{"B":{}}})", s(Object{{"A", Object{{"B", Object{}}}}}));
  47   EXPECT_EQ(R"({"A":{"B":{"X":"Y"}}})",
  48             s(Object{{"A", Object{{"B", Object{{"X", "Y"}}}}}}));
  49   EXPECT_EQ("null", s(llvm::Optional<double>()));
  50   EXPECT_EQ("2.5", s(llvm::Optional<double>(2.5)));
  51   EXPECT_EQ("[[2.5,null]]", s(std::vector<std::vector<llvm::Optional<double>>>{
  52                                  {2.5, llvm::None}}));
  53 }
  54
  55 TEST(JSONTest, StringOwnership) {
  56   char X[] = "Hello";
  57   Value Alias = static_cast<const char *>(X);
  58   X[1] = 'a';
  59   EXPECT_EQ(R"("Hallo")", s(Alias));
  60
  61   std::string Y = "Hello";
  62   Value Copy = Y;
  63   Y[1] = 'a';
  64   EXPECT_EQ(R"("Hello")", s(Copy));
  65 }
  66
  67 TEST(JSONTest, CanonicalOutput) {
  68   // Objects are sorted (but arrays aren't)!
  69   EXPECT_EQ(R"({"a":1,"b":2,"c":3})", s(Object{{"a", 1}, {"c", 3}, {"b", 2}}));
  70   EXPECT_EQ(R"(["a","c","b"])", s({"a", "c", "b"}));
  71   EXPECT_EQ("3", s(3.0));
  72 }
  73
  74 TEST(JSONTest, Escaping) {
  75   std::string Test = {
  76       0,                    // Strings may contain nulls.
  77       '\b',   '\f',         // Have mnemonics, but we escape numerically.
  78       '\r',   '\n',   '\t', // Escaped with mnemonics.
  79       'S',    '\"',   '\\', // Printable ASCII characters.
  80       '\x7f',               // Delete is not escaped.
  81       '\xce', '\x94',       // Non-ASCII UTF-8 is not escaped.
  82   };
  83
  84   std::string TestString = R"("\u0000\u0008\u000c\r\n\tS\"\\)"
  85                            "\x7f\xCE\x94\"";
  86
  87   EXPECT_EQ(TestString, s(Test));
  88
  89   EXPECT_EQ(R"({"object keys are\nescaped":true})",
  90             s(Object{{"object keys are\nescaped", true}}));
  91 }
  92
  93 TEST(JSONTest, PrettyPrinting) {
  94   const char Str[] = R"({
  95   "empty_array": [],
  96   "empty_object": {},
  97   "full_array": [
  98     1,
  99     null
 100   ],
 101   "full_object": {
 102     "nested_array": [
 103       {
 104         "property": "value"
 105       }
 106     ]
 107   }
 108 })";
 109
 110   EXPECT_EQ(Str, sp(Object{
 111                      {"empty_object", Object{}},
 112                      {"empty_array", {}},
 113                      {"full_array", {1, nullptr}},
 114                      {"full_object",
 115                       Object{
 116                           {"nested_array",
 117                            {Object{
 118                                {"property", "value"},
 119                            }}},
 120                       }},
 121                  }));
 122 }
 123
 124 TEST(JSONTest, Array) {
 125   Array A{1, 2};
 126   A.emplace_back(3);
 127   A.emplace(++A.begin(), 0);
 128   A.push_back(4);
 129   A.insert(++++A.begin(), 99);
 130
 131   EXPECT_EQ(A.size(), 6u);
 132   EXPECT_EQ(R"([1,0,99,2,3,4])", s(std::move(A)));
 133 }
 134
 135 TEST(JSONTest, Object) {
 136   Object O{{"a", 1}, {"b", 2}, {"c", 3}};
 137   EXPECT_TRUE(O.try_emplace("d", 4).second);
 138   EXPECT_FALSE(O.try_emplace("a", 4).second);
 139
 140   auto D = O.find("d");
 141   EXPECT_FALSE(D == O.end());
 142   auto E = O.find("e");
 143   EXPECT_TRUE(E == O.end());
 144
 145   O.erase("b");
 146   O.erase(D);
 147   EXPECT_EQ(O.size(), 2u);
 148   EXPECT_EQ(R"({"a":1,"c":3})", s(std::move(O)));
 149 }
 150
 151 TEST(JSONTest, Parse) {
 152   auto Compare = [](llvm::StringRef S, Value Expected) {
 153     if (auto E = parse(S)) {
 154       // Compare both string forms and with operator==, in case we have bugs.
 155       EXPECT_EQ(*E, Expected);
 156       EXPECT_EQ(sp(*E), sp(Expected));
 157     } else {
 158       handleAllErrors(E.takeError(), [S](const llvm::ErrorInfoBase &E) {
 159         FAIL() << "Failed to parse JSON >>> " << S << " <<<: " << E.message();
 160       });
 161     }
 162   };
 163
 164   Compare(R"(true)", true);
 165   Compare(R"(false)", false);
 166   Compare(R"(null)", nullptr);
 167
 168   Compare(R"(42)", 42);
 169   Compare(R"(2.5)", 2.5);
 170   Compare(R"(2e50)", 2e50);
 171   Compare(R"(1.2e3456789)", std::numeric_limits<double>::infinity());
 172
 173   Compare(R"("foo")", "foo");
 174   Compare(R"("\"\\\b\f\n\r\t")", "\"\\\b\f\n\r\t");
 175   Compare(R"("\u0000")", llvm::StringRef("\0", 1));
 176   Compare("\"\x7f\"", "\x7f");
 177   Compare(R"("\ud801\udc37")", u8"\U00010437"); // UTF16 surrogate pair escape.
 178   Compare("\"\xE2\x82\xAC\xF0\x9D\x84\x9E\"", u8"\u20ac\U0001d11e"); // UTF8
 179   Compare(
 180       R"("LoneLeading=\ud801, LoneTrailing=\udc01, LeadingLeadingTrailing=\ud801\ud801\udc37")",
 181       u8"LoneLeading=\ufffd, LoneTrailing=\ufffd, "
 182       u8"LeadingLeadingTrailing=\ufffd\U00010437"); // Invalid unicode.
 183
 184   Compare(R"({"":0,"":0})", Object{{"", 0}});
 185   Compare(R"({"obj":{},"arr":[]})", Object{{"obj", Object{}}, {"arr", {}}});
 186   Compare(R"({"\n":{"\u0000":[[[[]]]]}})",
 187           Object{{"\n", Object{
 188                             {llvm::StringRef("\0", 1), {{{{}}}}},
 189                         }}});
 190   Compare("\r[\n\t] ", {});
 191 }
 192
 193 TEST(JSONTest, ParseErrors) {
 194   auto ExpectErr = [](llvm::StringRef Msg, llvm::StringRef S) {
 195     if (auto E = parse(S)) {
 196       // Compare both string forms and with operator==, in case we have bugs.
 197       FAIL() << "Parsed JSON >>> " << S << " <<< but wanted error: " << Msg;
 198     } else {
 199       handleAllErrors(E.takeError(), [S, Msg](const llvm::ErrorInfoBase &E) {
 200         EXPECT_THAT(E.message(), testing::HasSubstr(std::string(Msg))) << S;
 201       });
 202     }
 203   };
 204   ExpectErr("Unexpected EOF", "");
 205   ExpectErr("Unexpected EOF", "[");
 206   ExpectErr("Text after end of document", "[][]");
 207   ExpectErr("Invalid JSON value (false?)", "fuzzy");
 208   ExpectErr("Expected , or ]", "[2?]");
 209   ExpectErr("Expected object key", "{a:2}");
 210   ExpectErr("Expected : after object key", R"({"a",2})");
 211   ExpectErr("Expected , or } after object property", R"({"a":2 "b":3})");
 212   ExpectErr("Invalid JSON value", R"([&%!])");
 213   ExpectErr("Invalid JSON value (number?)", "1e1.0");
 214   ExpectErr("Unterminated string", R"("abc\"def)");
 215   ExpectErr("Control character in string", "\"abc\ndef\"");
 216   ExpectErr("Invalid escape sequence", R"("\030")");
 217   ExpectErr("Invalid \\u escape sequence", R"("\usuck")");
 218   ExpectErr("[3:3, byte=19]", R"({
 219   "valid": 1,
 220   invalid: 2
 221 })");
 222   ExpectErr("Invalid UTF-8 sequence", "\"\xC0\x80\""); // WTF-8 null
 223 }
 224
 225 // Direct tests of isUTF8 and fixUTF8. Internal uses are also tested elsewhere.
 226 TEST(JSONTest, UTF8) {
 227   for (const char *Valid : {
 228            "this is ASCII text",
 229            "thïs tëxt häs BMP chäräctërs",
 230            "𐌶𐌰L𐌾𐍈 C𐍈𐌼𐌴𐍃",
 231        }) {
 232     EXPECT_TRUE(isUTF8(Valid)) << Valid;
 233     EXPECT_EQ(fixUTF8(Valid), Valid);
 234   }
 235   for (auto Invalid : std::vector<std::pair<const char *, const char *>>{
 236            {"lone trailing \x81\x82 bytes", "lone trailing �� bytes"},
 237            {"missing trailing \xD0 bytes", "missing trailing � bytes"},
 238            {"truncated character \xD0", "truncated character �"},
 239            {"not \xC1\x80 the \xE0\x9f\xBF shortest \xF0\x83\x83\x83 encoding",
 240             "not �� the ��� shortest ���� encoding"},
 241            {"too \xF9\x80\x80\x80\x80 long", "too ����� long"},
 242            {"surrogate \xED\xA0\x80 invalid \xF4\x90\x80\x80",
 243             "surrogate ��� invalid ����"}}) {
 244     EXPECT_FALSE(isUTF8(Invalid.first)) << Invalid.first;
 245     EXPECT_EQ(fixUTF8(Invalid.first), Invalid.second);
 246   }
 247 }
 248
 249 TEST(JSONTest, Inspection) {
 250   llvm::Expected<Value> Doc = parse(R"(
 251     {
 252       "null": null,
 253       "boolean": false,
 254       "number": 2.78,
 255       "string": "json",
 256       "array": [null, true, 3.14, "hello", [1,2,3], {"time": "arrow"}],
 257       "object": {"fruit": "banana"}
 258     }
 259   )");
 260   EXPECT_TRUE(!!Doc);
 261
 262   Object *O = Doc->getAsObject();
 263   ASSERT_TRUE(O);
 264
 265   EXPECT_FALSE(O->getNull("missing"));
 266   EXPECT_FALSE(O->getNull("boolean"));
 267   EXPECT_TRUE(O->getNull("null"));
 268
 269   EXPECT_EQ(O->getNumber("number"), llvm::Optional<double>(2.78));
 270   EXPECT_FALSE(O->getInteger("number"));
 271   EXPECT_EQ(O->getString("string"), llvm::Optional<llvm::StringRef>("json"));
 272   ASSERT_FALSE(O->getObject("missing"));
 273   ASSERT_FALSE(O->getObject("array"));
 274   ASSERT_TRUE(O->getObject("object"));
 275   EXPECT_EQ(*O->getObject("object"), (Object{{"fruit", "banana"}}));
 276
 277   Array *A = O->getArray("array");
 278   ASSERT_TRUE(A);
 279   EXPECT_EQ((*A)[1].getAsBoolean(), llvm::Optional<bool>(true));
 280   ASSERT_TRUE((*A)[4].getAsArray());
 281   EXPECT_EQ(*(*A)[4].getAsArray(), (Array{1, 2, 3}));
 282   EXPECT_EQ((*(*A)[4].getAsArray())[1].getAsInteger(),
 283             llvm::Optional<int64_t>(2));
 284   int I = 0;
 285   for (Value &E : *A) {
 286     if (I++ == 5) {
 287       ASSERT_TRUE(E.getAsObject());
 288       EXPECT_EQ(E.getAsObject()->getString("time"),
 289                 llvm::Optional<llvm::StringRef>("arrow"));
 290     } else
 291       EXPECT_FALSE(E.getAsObject());
 292   }
 293 }
 294
 295 // Verify special integer handling - we try to preserve exact int64 values.
 296 TEST(JSONTest, Integers) {
 297   struct {
 298     const char *Desc;
 299     Value Val;
 300     const char *Str;
 301     llvm::Optional<int64_t> AsInt;
 302     llvm::Optional<double> AsNumber;
 303   } TestCases[] = {
 304       {
 305           "Non-integer. Stored as double, not convertible.",
 306           double{1.5},
 307           "1.5",
 308           llvm::None,
 309           1.5,
 310       },
 311
 312       {
 313           "Integer, not exact double. Stored as int64, convertible.",
 314           int64_t{0x4000000000000001},
 315           "4611686018427387905",
 316           int64_t{0x4000000000000001},
 317           double{0x4000000000000000},
 318       },
 319
 320       {
 321           "Negative integer, not exact double. Stored as int64, convertible.",
 322           int64_t{-0x4000000000000001},
 323           "-4611686018427387905",
 324           int64_t{-0x4000000000000001},
 325           double{-0x4000000000000000},
 326       },
 327
 328       // PR46470,
 329       // https://developercommunity.visualstudio.com/content/problem/1093399/incorrect-result-when-printing-6917529027641081856.html
 330 #if !defined(_MSC_VER) || _MSC_VER < 1926
 331       {
 332           "Dynamically exact integer. Stored as double, convertible.",
 333           double{0x6000000000000000},
 334           "6.9175290276410819e+18",
 335           int64_t{0x6000000000000000},
 336           double{0x6000000000000000},
 337       },
 338 #endif
 339
 340       {
 341           "Dynamically integer, >64 bits. Stored as double, not convertible.",
 342           1.5 * double{0x8000000000000000},
 343           "1.3835058055282164e+19",
 344           llvm::None,
 345           1.5 * double{0x8000000000000000},
 346       },
 347   };
 348   for (const auto &T : TestCases) {
 349     EXPECT_EQ(T.Str, s(T.Val)) << T.Desc;
 350     llvm::Expected<Value> Doc = parse(T.Str);
 351     EXPECT_TRUE(!!Doc) << T.Desc;
 352     EXPECT_EQ(Doc->getAsInteger(), T.AsInt) << T.Desc;
 353     EXPECT_EQ(Doc->getAsNumber(), T.AsNumber) << T.Desc;
 354     EXPECT_EQ(T.Val, *Doc) << T.Desc;
 355     EXPECT_EQ(T.Str, s(*Doc)) << T.Desc;
 356   }
 357 }
 358
 359 // Verify uint64_t type.
 360 TEST(JSONTest, U64Integers) {
 361   Value Val = uint64_t{3100100100};
 362   uint64_t Var = 3100100100;
 363   EXPECT_EQ(Val, Var);
 364
 365   // Test the parse() part.
 366   const char *Str = "4611686018427387905";
 367   llvm::Expected<Value> Doc = parse(Str);
 368
 369   EXPECT_TRUE(!!Doc);
 370   EXPECT_EQ(Doc->getAsInteger(), int64_t{4611686018427387905});
 371   EXPECT_EQ(Doc->getAsUINT64(), uint64_t{4611686018427387905});
 372
 373   const char *Str2 = "-78278238238328222";
 374   llvm::Expected<Value> Doc2 = parse(Str2);
 375   EXPECT_TRUE(!!Doc2);
 376   EXPECT_EQ(Doc2->getAsInteger(), int64_t{-78278238238328222});
 377   EXPECT_EQ(Doc2->getAsUINT64(), llvm::None);
 378 }
 379
 380 // Sample struct with typical JSON-mapping rules.
 381 struct CustomStruct {
 382   CustomStruct() : B(false) {}
 383   CustomStruct(std::string S, llvm::Optional<int> I, bool B)
 384       : S(S), I(I), B(B) {}
 385   std::string S;
 386   llvm::Optional<int> I;
 387   bool B;
 388 };
 389 inline bool operator==(const CustomStruct &L, const CustomStruct &R) {
 390   return L.S == R.S && L.I == R.I && L.B == R.B;
 391 }
 392 inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
 393                                      const CustomStruct &S) {
 394   return OS << "(" << S.S << ", " << (S.I ? std::to_string(*S.I) : "None")
 395             << ", " << S.B << ")";
 396 }
 397 bool fromJSON(const Value &E, CustomStruct &R, Path P) {
 398   ObjectMapper O(E, P);
 399   return O && O.map("str", R.S) && O.map("int", R.I) &&
 400          O.mapOptional("bool", R.B);
 401 }
 402
 403 static std::string errorContext(const Value &V, const Path::Root &R) {
 404   std::string Context;
 405   llvm::raw_string_ostream OS(Context);
 406   R.printErrorContext(V, OS);
 407   return OS.str();
 408 }
 409
 410 TEST(JSONTest, Deserialize) {
 411   std::map<std::string, std::vector<CustomStruct>> R;
 412   CustomStruct ExpectedStruct = {"foo", 42, true};
 413   std::map<std::string, std::vector<CustomStruct>> Expected;
 414   Value J = Object{{"foo", Array{
 415                                Object{
 416                                    {"str", "foo"},
 417                                    {"int", 42},
 418                                    {"bool", true},
 419                                    {"unknown", "ignored"},
 420                                },
 421                                Object{{"str", "bar"}},
 422                            }}};
 423   Expected["foo"] = {
 424       CustomStruct("foo", 42, true),
 425       CustomStruct("bar", llvm::None, false),
 426   };
 427   Path::Root Root("CustomStruct");
 428   ASSERT_TRUE(fromJSON(J, R, Root));
 429   EXPECT_EQ(R, Expected);
 430
 431   (*J.getAsObject()->getArray("foo"))[0] = 123;
 432   ASSERT_FALSE(fromJSON(J, R, Root));
 433   EXPECT_EQ("expected object at CustomStruct.foo[0]",
 434             toString(Root.getError()));
 435   const char *ExpectedDump = R"({
 436   "foo": [
 437     /* error: expected object */
 438     123,
 439     { ... }
 440   ]
 441 })";
 442   EXPECT_EQ(ExpectedDump, errorContext(J, Root));
 443
 444   CustomStruct V;
 445   EXPECT_FALSE(fromJSON(nullptr, V, Root));
 446   EXPECT_EQ("expected object when parsing CustomStruct",
 447             toString(Root.getError()));
 448
 449   EXPECT_FALSE(fromJSON(Object{}, V, Root));
 450   EXPECT_EQ("missing value at CustomStruct.str", toString(Root.getError()));
 451
 452   EXPECT_FALSE(fromJSON(Object{{"str", 1}}, V, Root));
 453   EXPECT_EQ("expected string at CustomStruct.str", toString(Root.getError()));
 454
 455   // Optional<T> must parse as the correct type if present.
 456   EXPECT_FALSE(fromJSON(Object{{"str", "1"}, {"int", "string"}}, V, Root));
 457   EXPECT_EQ("expected integer at CustomStruct.int", toString(Root.getError()));
 458
 459   // mapOptional must parse as the correct type if present.
 460   EXPECT_FALSE(fromJSON(Object{{"str", "1"}, {"bool", "string"}}, V, Root));
 461   EXPECT_EQ("expected boolean at CustomStruct.bool", toString(Root.getError()));
 462 }
 463
 464 TEST(JSONTest, ParseDeserialize) {
 465   auto E = parse<std::vector<CustomStruct>>(R"json(
 466     [{"str": "foo", "int": 42}, {"int": 42}]
 467   )json");
 468   EXPECT_THAT_EXPECTED(E, FailedWithMessage("missing value at (root)[1].str"));
 469
 470   E = parse<std::vector<CustomStruct>>(R"json(
 471     [{"str": "foo", "int": 42}, {"str": "bar"}
 472   )json");
 473   EXPECT_THAT_EXPECTED(
 474       E,
 475       FailedWithMessage("[3:2, byte=50]: Expected , or ] after array element"));
 476
 477   E = parse<std::vector<CustomStruct>>(R"json(
 478     [{"str": "foo", "int": 42}]
 479   )json");
 480   EXPECT_THAT_EXPECTED(E, Succeeded());
 481   EXPECT_THAT(*E, testing::SizeIs(1));
 482 }
 483
 484 TEST(JSONTest, Stream) {
 485   auto StreamStuff = [](unsigned Indent) {
 486     std::string S;
 487     llvm::raw_string_ostream OS(S);
 488     OStream J(OS, Indent);
 489     J.comment("top*/level");
 490     J.object([&] {
 491       J.attributeArray("foo", [&] {
 492         J.value(nullptr);
 493         J.comment("element");
 494         J.value(42.5);
 495         J.arrayBegin();
 496         J.value(43);
 497         J.arrayEnd();
 498         J.rawValue([](raw_ostream &OS) { OS << "'unverified\nraw value'"; });
 499       });
 500       J.comment("attribute");
 501       J.attributeBegin("bar");
 502       J.comment("attribute value");
 503       J.objectBegin();
 504       J.objectEnd();
 505       J.attributeEnd();
 506       J.attribute("baz", "xyz");
 507     });
 508     return OS.str();
 509   };
 510
 511   const char *Plain =
 512       R"(/*top* /level*/{"foo":[null,/*element*/42.5,[43],'unverified
 513 raw value'],/*attribute*/"bar":/*attribute value*/{},"baz":"xyz"})";
 514   EXPECT_EQ(Plain, StreamStuff(0));
 515   const char *Pretty = R"(/* top* /level */
 516 {
 517   "foo": [
 518     null,
 519     /* element */
 520     42.5,
 521     [
 522       43
 523     ],
 524     'unverified
 525 raw value'
 526   ],
 527   /* attribute */
 528   "bar": /* attribute value */ {},
 529   "baz": "xyz"
 530 })";
 531   EXPECT_EQ(Pretty, StreamStuff(2));
 532 }
 533
 534 TEST(JSONTest, Path) {
 535   Path::Root R("foo");
 536   Path P = R, A = P.field("a"), B = P.field("b");
 537   P.report("oh no");
 538   EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("oh no when parsing foo"));
 539   A.index(1).field("c").index(2).report("boom");
 540   EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("boom at foo.a[1].c[2]"));
 541   B.field("d").field("e").report("bam");
 542   EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("bam at foo.b.d.e"));
 543
 544   Value V = Object{
 545       {"a", Array{42}},
 546       {"b",
 547        Object{{"d",
 548                Object{
 549                    {"e", Array{1, Object{{"x", "y"}}}},
 550                    {"f", "a moderately long string: 48 characters in total"},
 551                }}}},
 552   };
 553   const char *Expected = R"({
 554   "a": [ ... ],
 555   "b": {
 556     "d": {
 557       "e": /* error: bam */ [
 558         1,
 559         { ... }
 560       ],
 561       "f": "a moderately long string: 48 characte..."
 562     }
 563   }
 564 })";
 565   EXPECT_EQ(Expected, errorContext(V, R));
 566 }
 567
 568 } // namespace
 569 } // namespace json
 570 } // namespace llvm