Blink-compatible serialization of dictionary-like objects.

test/unittests/value-serializer-unittest.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/value-serializer.h"
 
 #include <algorithm>
 #include <string>
 
 #include "include/v8.h"
@@ skipping 20 matching lines @@
 
   template <typename InputFunctor, typename OutputFunctor>
   void RoundTripTest(const InputFunctor& input_functor,
                      const OutputFunctor& output_functor) {
     EncodeTest(input_functor,
                [this, &output_functor](const std::vector<uint8_t>& data) {
                  DecodeTest(data, output_functor);
                });
   }
 
+  // Variant for the common case where a script is used to build the original
+  // value.
+  template <typename OutputFunctor>
+  void RoundTripTest(const char* source, const OutputFunctor& output_functor) {
+    RoundTripTest([this, source]() { return EvaluateScriptForInput(source); },
+                  output_functor);
+  }
+
+  Maybe<std::vector<uint8_t>> DoEncode(Local<Value> value) {
+    // This approximates what the API implementation would do.
+    // TODO(jbroman): Use the public API once it exists.
+    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
+    i::HandleScope handle_scope(internal_isolate);
+    i::ValueSerializer serializer(internal_isolate);
+    serializer.WriteHeader();
+    if (serializer.WriteObject(Utils::OpenHandle(*value)).FromMaybe(false))
+      return Just(serializer.ReleaseBuffer());

[Jakob Kummerow, 2016/08/17 13:00:15]

nit: braces please

[jbroman, 2016/08/17 14:05:09]

Done.

+    if (internal_isolate->has_pending_exception())
+      internal_isolate->OptionalRescheduleException(true);

[Jakob Kummerow, 2016/08/17 13:00:15]

nit: braces please

[jbroman, 2016/08/17 14:05:09]

Done. (I wish clang-format fixed this.)

+    return Nothing<std::vector<uint8_t>>();
+  }
+
   template <typename InputFunctor, typename EncodedDataFunctor>
   void EncodeTest(const InputFunctor& input_functor,
                   const EncodedDataFunctor& encoded_data_functor) {
     Context::Scope scope(serialization_context());
     TryCatch try_catch(isolate());
-    // TODO(jbroman): Use the public API once it exists.
     Local<Value> input_value = input_functor();
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
-    i::HandleScope handle_scope(internal_isolate);
-    i::ValueSerializer serializer;
-    serializer.WriteHeader();
-    ASSERT_TRUE(serializer.WriteObject(Utils::OpenHandle(*input_value))
-                    .FromMaybe(false));
+    std::vector<uint8_t> buffer;
+    ASSERT_TRUE(DoEncode(input_value).To(&buffer));
     ASSERT_FALSE(try_catch.HasCaught());
-    encoded_data_functor(serializer.ReleaseBuffer());
+    encoded_data_functor(buffer);
+  }
+
+  template <typename MessageFunctor>
+  void InvalidEncodeTest(const char* source, const MessageFunctor& functor) {
+    Context::Scope scope(serialization_context());
+    TryCatch try_catch(isolate());
+    Local<Value> input_value = EvaluateScriptForInput(source);
+    ASSERT_TRUE(DoEncode(input_value).IsNothing());
+    functor(try_catch.Message());
   }
 
   template <typename OutputFunctor>
   void DecodeTest(const std::vector<uint8_t>& data,
                   const OutputFunctor& output_functor) {
     Context::Scope scope(deserialization_context());
     TryCatch try_catch(isolate());
     // TODO(jbroman): Use the public API once it exists.
     i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
     i::HandleScope handle_scope(internal_isolate);
@@ skipping 315 matching lines @@
       [](const std::vector<uint8_t>& data) {
         // This is a sufficient but not necessary condition to be aligned.
         // Note that the third byte (0x00) is padding.
         const uint8_t expected_prefix[] = {0xff, 0x09, 0x00, 0x63, 0x94, 0x03};
         ASSERT_GT(data.size(), sizeof(expected_prefix) / sizeof(uint8_t));
         EXPECT_TRUE(std::equal(std::begin(expected_prefix),
                                std::end(expected_prefix), data.begin()));
       });
 }
 
+TEST_F(ValueSerializerTest, RoundTripDictionaryObject) {
+  // Empty object.
+  RoundTripTest("({})", [this](Local<Value> value) {
+    ASSERT_TRUE(value->IsObject());
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getPrototypeOf(result) === Object.prototype"));
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getOwnPropertyNames(result).length === 0"));
+  });
+  // String key.
+  RoundTripTest("({ a: 42 })", [this](Local<Value> value) {
+    ASSERT_TRUE(value->IsObject());
+    EXPECT_TRUE(EvaluateScriptForResultBool("result.hasOwnProperty('a')"));
+    EXPECT_TRUE(EvaluateScriptForResultBool("result.a === 42"));
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getOwnPropertyNames(result).length === 1"));
+  });
+  // Integer key (treated as a string, but may be encoded differently).
+  RoundTripTest("({ 42: 'a' })", [this](Local<Value> value) {
+    ASSERT_TRUE(value->IsObject());
+    EXPECT_TRUE(EvaluateScriptForResultBool("result.hasOwnProperty('42')"));
+    EXPECT_TRUE(EvaluateScriptForResultBool("result[42] === 'a'"));
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getOwnPropertyNames(result).length === 1"));
+  });
+  // Key order must be preserved.
+  RoundTripTest("({ x: 1, y: 2, a: 3 })", [this](Local<Value> value) {
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getOwnPropertyNames(result).toString() === 'x,y,a'"));
+  });
+  // A harder case of enumeration order.
+  // Indexes first, in order (but not 2^31 - 1, which is not an index), then the

[Jakob Kummerow, 2016/08/17 13:00:15]

nit: you mean "2^32 - 1".

[jbroman, 2016/08/17 14:05:09]

Indeed. Done.

+  // remaining (string) keys, in the order they were defined.
+  RoundTripTest(
+      "({ a: 2, 0xFFFFFFFF: 1, 0xFFFFFFFE: 3, 1: 0 })",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).toString() === "
+            "'1,4294967294,a,4294967295'"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.a === 2"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[0xFFFFFFFF] === 1"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[0xFFFFFFFE] === 3"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[1] === 0"));
+      });
+  // This detects a fairly subtle case: the object itself must be in the map
+  // before its properties are deserialized, so that references to it can be
+  // resolved.
+  RoundTripTest(
+      "(() => { var y = {}; y.self = y; return y; })()",
+      [this](Local<Value> value) {
+        ASSERT_TRUE(value->IsObject());
+        EXPECT_TRUE(EvaluateScriptForResultBool("result === result.self"));
+      });
+}
+
+TEST_F(ValueSerializerTest, DecodeDictionaryObject) {
+  // Empty object.
+  DecodeTest({0xff, 0x09, 0x3f, 0x00, 0x6f, 0x7b, 0x00, 0x00},
+             [this](Local<Value> value) {
+               ASSERT_TRUE(value->IsObject());
+               EXPECT_TRUE(EvaluateScriptForResultBool(
+                   "Object.getPrototypeOf(result) === Object.prototype"));
+               EXPECT_TRUE(EvaluateScriptForResultBool(
+                   "Object.getOwnPropertyNames(result).length === 0"));
+             });
+  // String key.
+  DecodeTest(
+      {0xff, 0x09, 0x3f, 0x00, 0x6f, 0x3f, 0x01, 0x53, 0x01, 0x61, 0x3f, 0x01,
+       0x49, 0x54, 0x7b, 0x01},
+      [this](Local<Value> value) {
+        ASSERT_TRUE(value->IsObject());
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.hasOwnProperty('a')"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.a === 42"));
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).length === 1"));
+      });
+  // Integer key (treated as a string, but may be encoded differently).
+  DecodeTest(
+      {0xff, 0x09, 0x3f, 0x00, 0x6f, 0x3f, 0x01, 0x49, 0x54, 0x3f, 0x01, 0x53,
+       0x01, 0x61, 0x7b, 0x01},
+      [this](Local<Value> value) {
+        ASSERT_TRUE(value->IsObject());
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.hasOwnProperty('42')"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[42] === 'a'"));
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).length === 1"));
+      });
+  // Key order must be preserved.
+  DecodeTest(
+      {0xff, 0x09, 0x3f, 0x00, 0x6f, 0x3f, 0x01, 0x53, 0x01, 0x78, 0x3f, 0x01,
+       0x49, 0x02, 0x3f, 0x01, 0x53, 0x01, 0x79, 0x3f, 0x01, 0x49, 0x04, 0x3f,
+       0x01, 0x53, 0x01, 0x61, 0x3f, 0x01, 0x49, 0x06, 0x7b, 0x03},
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).toString() === 'x,y,a'"));
+      });
+  // A harder case of enumeration order.
+  DecodeTest(
+      {0xff, 0x09, 0x3f, 0x00, 0x6f, 0x3f, 0x01, 0x49, 0x02, 0x3f, 0x01,
+       0x49, 0x00, 0x3f, 0x01, 0x55, 0xfe, 0xff, 0xff, 0xff, 0x0f, 0x3f,
+       0x01, 0x49, 0x06, 0x3f, 0x01, 0x53, 0x01, 0x61, 0x3f, 0x01, 0x49,
+       0x04, 0x3f, 0x01, 0x53, 0x0a, 0x34, 0x32, 0x39, 0x34, 0x39, 0x36,
+       0x37, 0x32, 0x39, 0x35, 0x3f, 0x01, 0x49, 0x02, 0x7b, 0x04},
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).toString() === "
+            "'1,4294967294,a,4294967295'"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.a === 2"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[0xFFFFFFFF] === 1"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[0xFFFFFFFE] === 3"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result[1] === 0"));
+      });
+  // This detects a fairly subtle case: the object itself must be in the map
+  // before its properties are deserialized, so that references to it can be
+  // resolved.
+  DecodeTest(
+      {0xff, 0x09, 0x3f, 0x00, 0x6f, 0x3f, 0x01, 0x53, 0x04, 0x73,
+       0x65, 0x6c, 0x66, 0x3f, 0x01, 0x5e, 0x00, 0x7b, 0x01, 0x00},
+      [this](Local<Value> value) {
+        ASSERT_TRUE(value->IsObject());
+        EXPECT_TRUE(EvaluateScriptForResultBool("result === result.self"));
+      });
+}
+
+TEST_F(ValueSerializerTest, RoundTripOnlyOwnEnumerableStringKeys) {
+  // Only "own" properties should be serialized, not ones on the prototype.
+  RoundTripTest("(() => { var x = {}; x.__proto__ = {a: 4}; return x; })()",
+                [this](Local<Value> value) {
+                  EXPECT_TRUE(EvaluateScriptForResultBool("!('a' in result)"));
+                });
+  // Only enumerable properties should be serialized.
+  RoundTripTest(
+      "(() => {"
+      "  var x = {};"
+      "  Object.defineProperty(x, 'a', {value: 1, enumerable: false});"
+      "  return x;"
+      "})()",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool("!('a' in result)"));
+      });
+  // Symbol keys should not be serialized.
+  RoundTripTest("({ [Symbol()]: 4 })", [this](Local<Value> value) {
+    EXPECT_TRUE(EvaluateScriptForResultBool(
+        "Object.getOwnPropertySymbols(result).length === 0"));
+  });
+}
+
+TEST_F(ValueSerializerTest, RoundTripTrickyGetters) {
+  // Keys are enumerated before any setters are called, but if there is no own
+  // property when the value is to be read, then it should not be serialized.
+  RoundTripTest("({ get a() { delete this.b; return 1; }, b: 2 })",
+                [this](Local<Value> value) {
+                  EXPECT_TRUE(EvaluateScriptForResultBool("!('b' in result)"));
+                });
+  // Keys added after the property enumeration should not be serialized.
+  RoundTripTest("({ get a() { this.b = 3; }})", [this](Local<Value> value) {
+    EXPECT_TRUE(EvaluateScriptForResultBool("!('b' in result)"));
+  });
+  // But if you remove a key and add it back, that's fine. But it will appear in
+  // the original place in enumeration order.
+  RoundTripTest(
+      "({ get a() { delete this.b; this.b = 4; }, b: 2, c: 3 })",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "Object.getOwnPropertyNames(result).toString() === 'a,b,c'"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.b === 4"));
+      });
+  // Similarly, it only matters if a property was enumerable when the
+  // enumeration happened.
+  RoundTripTest(
+      "({ get a() {"
+      "    Object.defineProperty(this, 'b', {value: 2, enumerable: false});"
+      "}, b: 1})",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.b === 2"));
+      });
+  RoundTripTest(
+      "(() => {"
+      "  var x = {"
+      "    get a() {"
+      "      Object.defineProperty(this, 'b', {value: 2, enumerable: true});"
+      "    }"
+      "  };"
+      "  Object.defineProperty(x, 'b',"
+      "      {value: 1, enumerable: false, configurable: true});"
+      "  return x;"
+      "})()",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool("!('b' in result)"));
+      });
+  // The property also should not be read if it can only be found on the
+  // prototype chain (but not as an own property) after enumeration.
+  RoundTripTest(
+      "(() => {"
+      "  var x = { get a() { delete this.b; }, b: 1 };"
+      "  x.__proto__ = { b: 0 };"
+      "  return x;"
+      "})()",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool("!('b' in result)"));
+      });
+  // If an exception is thrown by script, encoding must fail and the exception
+  // must be thrown.
+  InvalidEncodeTest("({ get a() { throw new Error('sentinel'); } })",
+                    [](Local<Message> message) {
+                      ASSERT_FALSE(message.IsEmpty());
+                      EXPECT_NE(std::string::npos,
+                                Utf8Value(message->Get()).find("sentinel"));
+                    });
+}
+
 }  // namespace
 }  // namespace v8