From 487b8743cbc79fcda2e361e686d60088bf3652ee Mon Sep 17 00:00:00 2001
From: Hakkyu Kim <hakkyu.kim@samsung.com>
Date: Fri, 23 Jul 2021 06:26:01 +0900
Subject: [PATCH] Removes unnecessary error message: "Invalid read in
 StandardCodecByteStreamReader" for cpp BasicMessageChannel
 (flutter/engine#26956)

---
 .../common/client_wrapper/standard_codec.cc   |  3 +++
 .../standard_message_codec_unittests.cc       | 25 +++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/engine/src/flutter/shell/platform/common/client_wrapper/standard_codec.cc b/engine/src/flutter/shell/platform/common/client_wrapper/standard_codec.cc
index e37e4a18dc4..d7dd89d5857 100644
--- a/engine/src/flutter/shell/platform/common/client_wrapper/standard_codec.cc
+++ b/engine/src/flutter/shell/platform/common/client_wrapper/standard_codec.cc
@@ -318,6 +318,9 @@ StandardMessageCodec::~StandardMessageCodec() = default;
 std::unique_ptr<EncodableValue> StandardMessageCodec::DecodeMessageInternal(
     const uint8_t* binary_message,
     size_t message_size) const {
+  if (!binary_message) {
+    return std::make_unique<EncodableValue>();
+  }
   ByteBufferStreamReader stream(binary_message, message_size);
   return std::make_unique<EncodableValue>(serializer_->ReadValue(&stream));
 }
diff --git a/engine/src/flutter/shell/platform/common/client_wrapper/standard_message_codec_unittests.cc b/engine/src/flutter/shell/platform/common/client_wrapper/standard_message_codec_unittests.cc
index c7a92427df6..9dea217adb3 100644
--- a/engine/src/flutter/shell/platform/common/client_wrapper/standard_message_codec_unittests.cc
+++ b/engine/src/flutter/shell/platform/common/client_wrapper/standard_message_codec_unittests.cc
@@ -8,10 +8,23 @@
 #include <vector>
 
 #include "flutter/shell/platform/common/client_wrapper/testing/test_codec_extensions.h"
+#include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 namespace flutter {
 
+namespace {
+
+class MockStandardCodecSerializer : public StandardCodecSerializer {
+ public:
+  MOCK_CONST_METHOD2(WriteValue,
+                     void(const EncodableValue& value,
+                          ByteStreamWriter* stream));
+  MOCK_CONST_METHOD2(ReadValueOfType,
+                     EncodableValue(uint8_t type, ByteStreamReader* stream));
+};
+}  // namespace
+
 // Validates round-trip encoding and decoding of |value|, and checks that the
 // encoded value matches |expected_encoding|.
 //
@@ -68,6 +81,18 @@ TEST(StandardMessageCodec, CanEncodeAndDecodeNull) {
   CheckEncodeDecode(EncodableValue(), bytes);
 }
 
+TEST(StandardMessageCodec, CanDecodeEmptyBytesAsNullWithoutCallingSerializer) {
+  std::vector<uint8_t> bytes = {};
+  const MockStandardCodecSerializer serializer;
+  const StandardMessageCodec& codec =
+      StandardMessageCodec::GetInstance(&serializer);
+
+  auto decoded = codec.DecodeMessage(bytes);
+
+  EXPECT_EQ(EncodableValue(), *decoded);
+  EXPECT_CALL(serializer, ReadValueOfType(::testing::_, ::testing::_)).Times(0);
+}
+
 TEST(StandardMessageCodec, CanEncodeAndDecodeTrue) {
   std::vector<uint8_t> bytes = {0x01};
   CheckEncodeDecode(EncodableValue(true), bytes);