From 7683667b3ca136760f5765a33d954e19d3c9d9ec Mon Sep 17 00:00:00 2001
From: Benoit Blanchon <github@benoitblanchon.fr>
Date: Tue, 21 Aug 2018 18:07:41 +0200
Subject: [PATCH] Fixed `serializeJson(obj[key], dst)` (closes #794)

---
 CHANGELOG.md                            |  1 +
 src/ArduinoJson/Json/JsonSerializer.hpp |  2 +-
 test/JsonSerializer/CMakeLists.txt      |  1 +
 test/JsonSerializer/misc.cpp            | 46 +++++++++++++++++++++++++
 test/MsgPackSerializer/CMakeLists.txt   |  1 +
 test/MsgPackSerializer/misc.cpp         | 46 +++++++++++++++++++++++++
 6 files changed, 96 insertions(+), 1 deletion(-)
 create mode 100644 test/JsonSerializer/misc.cpp
 create mode 100644 test/MsgPackSerializer/misc.cpp

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3757bd2..3bc9ae5d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ HEAD
 
 * Implemented reference semantics for `JsonVariant`
 * Replace `JsonPair`'s `key` and `value` with `key()` and `value()`
+* Fixed `serializeJson(obj[key], dst)` (issue #794)
 
 > ### BREAKING CHANGES
 >
diff --git a/src/ArduinoJson/Json/JsonSerializer.hpp b/src/ArduinoJson/Json/JsonSerializer.hpp
index 494075bc..5891ff69 100644
--- a/src/ArduinoJson/Json/JsonSerializer.hpp
+++ b/src/ArduinoJson/Json/JsonSerializer.hpp
@@ -91,7 +91,7 @@ class JsonSerializer {
 }  // namespace Internals
 
 template <typename TSource, typename TDestination>
-size_t serializeJson(TSource &source, TDestination &destination) {
+size_t serializeJson(const TSource &source, TDestination &destination) {
   using namespace Internals;
   return serialize<JsonSerializer>(source, destination);
 }
diff --git a/test/JsonSerializer/CMakeLists.txt b/test/JsonSerializer/CMakeLists.txt
index 1dc605dc..9fe4711b 100644
--- a/test/JsonSerializer/CMakeLists.txt
+++ b/test/JsonSerializer/CMakeLists.txt
@@ -8,6 +8,7 @@ add_executable(JsonSerializerTests
 	JsonObject.cpp
 	JsonObjectPretty.cpp
 	JsonVariant.cpp
+	misc.cpp
 	std_stream.cpp
 	std_string.cpp
 )
diff --git a/test/JsonSerializer/misc.cpp b/test/JsonSerializer/misc.cpp
new file mode 100644
index 00000000..f4bed63a
--- /dev/null
+++ b/test/JsonSerializer/misc.cpp
@@ -0,0 +1,46 @@
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <limits>
+
+template <typename T>
+void check(T value, const std::string &expected) {
+  DynamicJsonDocument doc;
+  doc.to<JsonVariant>().set(value);
+  char buffer[256] = "";
+  size_t returnValue = serializeJson(doc, buffer, sizeof(buffer));
+  REQUIRE(expected == buffer);
+  REQUIRE(expected.size() == returnValue);
+}
+
+TEST_CASE("serializeJson(JsonObjectSubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "{\"hello\":42}");
+  JsonObject obj = doc.as<JsonObject>();
+  std::string result;
+
+  serializeJson(obj["hello"], result);
+
+  REQUIRE(result == "42");
+}
+
+TEST_CASE("serializeJson(JsonArraySubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "[42]");
+  JsonArray arr = doc.as<JsonArray>();
+  std::string result;
+
+  serializeJson(arr[0], result);
+
+  REQUIRE(result == "42");
+}
+
+TEST_CASE("serializeJson(JsonVariantSubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "[42]");
+  JsonVariant var = doc.as<JsonVariant>();
+  std::string result;
+
+  serializeJson(var[0], result);
+
+  REQUIRE(result == "42");
+}
diff --git a/test/MsgPackSerializer/CMakeLists.txt b/test/MsgPackSerializer/CMakeLists.txt
index 20a8ce48..8ee09f00 100644
--- a/test/MsgPackSerializer/CMakeLists.txt
+++ b/test/MsgPackSerializer/CMakeLists.txt
@@ -5,6 +5,7 @@
 add_executable(MsgPackSerializerTests
 	destination_types.cpp
 	measure.cpp
+	misc.cpp
 	serializeArray.cpp
 	serializeObject.cpp
 	serializeVariant.cpp
diff --git a/test/MsgPackSerializer/misc.cpp b/test/MsgPackSerializer/misc.cpp
new file mode 100644
index 00000000..f6e20bc0
--- /dev/null
+++ b/test/MsgPackSerializer/misc.cpp
@@ -0,0 +1,46 @@
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <limits>
+
+template <typename T>
+void check(T value, const std::string &expected) {
+  DynamicJsonDocument doc;
+  doc.to<JsonVariant>().set(value);
+  char buffer[256] = "";
+  size_t returnValue = serializeMsgPack(doc, buffer, sizeof(buffer));
+  REQUIRE(expected == buffer);
+  REQUIRE(expected.size() == returnValue);
+}
+
+TEST_CASE("serializeMsgPack(JsonObjectSubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "{\"hello\":42}");
+  JsonObject obj = doc.as<JsonObject>();
+  std::string result;
+
+  serializeMsgPack(obj["hello"], result);
+
+  REQUIRE(result == "*");
+}
+
+TEST_CASE("serializeMsgPack(JsonArraySubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "[42]");
+  JsonArray arr = doc.as<JsonArray>();
+  std::string result;
+
+  serializeMsgPack(arr[0], result);
+
+  REQUIRE(result == "*");
+}
+
+TEST_CASE("serializeMsgPack(JsonVariantSubscript)") {
+  DynamicJsonDocument doc;
+  deserializeJson(doc, "[42]");
+  JsonVariant var = doc.as<JsonVariant>();
+  std::string result;
+
+  serializeMsgPack(var[0], result);
+
+  REQUIRE(result == "*");
+}