Merge "protozero: Finalize nested message when appending bytes" into …

…main

src/protozero/message.cc

@@ -90,6 +90,9 @@ void Message::AppendBytes(uint32_t field_id, const void* src, size_t size) {
 size_t Message::AppendScatteredBytes(uint32_t field_id,
                                      ContiguousMemoryRange* ranges,
                                      size_t num_ranges) {
+  if (nested_message_)
+    EndNestedMessage();
+
   size_t size = 0;
   for (size_t i = 0; i < num_ranges; ++i) {
     size += ranges[i].size();

src/protozero/message_unittest.cc

@@ -236,6 +236,28 @@ TEST_F(MessageTest, AppendScatteredBytes) {
   EXPECT_EQ("42424242", GetNextSerializedBytes(4));
 }
 
+TEST_F(MessageTest, AppendScatteredBytesFinalizesNestedMessage) {
+  Message* root_msg = NewMessage();
+
+  uint8_t buffer[42];
+  memset(buffer, 0x42, sizeof(buffer));
+
+  FakeChildMessage* nested_msg =
+      root_msg->BeginNestedMessage<FakeChildMessage>(9001 /* field_id */);
+  nested_msg->AppendVarInt(4 /* field_id */, 2);
+  uint8_t* nested_msg_size_field = nested_msg->size_field();
+
+  EXPECT_FALSE(nested_msg->is_finalized());
+  EXPECT_EQ(0u, *nested_msg_size_field);
+
+  ContiguousMemoryRange ranges[] = {{buffer, buffer + sizeof(buffer)}};
+  root_msg->AppendScatteredBytes(1 /* field_id */, ranges, 1);
+
+  // Nested message should have been finalized as a side effect of appending
+  // scattered bytes.
+  EXPECT_EQ(0x82u, *nested_msg_size_field);
+}
+
 // Checks that the size field of root and nested messages is properly written
 // on finalization.
 TEST_F(MessageTest, BackfillSizeOnFinalization) {