Check serialize/deserialize property in base_json_reader_fuzzer

Change-Id: I686d50b35736fb863ae83bb9a575e6e0cb0a8853
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790144Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695021}

base/json/json_reader_fuzzer.cc

@@ -3,8 +3,11 @@
 // found in the LICENSE file.
 
 #include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
 #include "base/values.h"
 
+namespace base {
+
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (size < 2)
@@ -15,11 +18,26 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   std::unique_ptr<char[]> input(new char[size - 1]);
   memcpy(input.get(), data, size - 1);
 
-  base::StringPiece input_string(input.get(), size - 1);
+  StringPiece input_string(input.get(), size - 1);
 
   const int options = data[size - 1];
 
-  base::JSONReader::ReadAndReturnValueWithError(input_string, options);
+  JSONReader::ValueWithError json_val =
+      JSONReader::ReadAndReturnValueWithError(input_string, options);
+
+  if (json_val.value) {
+    // Check that the value can be serialized and deserialized back to an
+    // equivalent |Value|.
+    const Value& value = json_val.value.value();
+    std::string serialized;
+    CHECK(JSONWriter::Write(value, &serialized));
+
+    Optional<Value> deserialized = JSONReader::Read(StringPiece(serialized));
+    CHECK(deserialized);
+    CHECK(value.Equals(&deserialized.value()));
+  }
 
   return 0;
 }
+
+}  // namespace base