Replace typedef with using

extras/tests/JsonDocument/ElementProxy.cpp

@@ -7,7 +7,7 @@
 
 #include "Literals.hpp"
 
-typedef ArduinoJson::detail::ElementProxy<JsonDocument&> ElementProxy;
+using ElementProxy = ArduinoJson::detail::ElementProxy<JsonDocument&>;
 
 TEST_CASE("ElementProxy::add()") {
   JsonDocument doc;

extras/tests/JsonDocument/MemberProxy.cpp

@@ -14,8 +14,8 @@
 using ArduinoJson::detail::sizeofArray;
 using ArduinoJson::detail::sizeofObject;
 
-typedef ArduinoJson::detail::MemberProxy<JsonDocument&, const char*>
-    MemberProxy;
+using MemberProxy =
+    ArduinoJson::detail::MemberProxy<JsonDocument&, const char*>;
 
 TEST_CASE("MemberProxy::add()") {
   JsonDocument doc;

extras/tests/JsonVariant/stl_containers.cpp

@@ -99,7 +99,7 @@ TEST_CASE("vector<int>") {
 }
 
 TEST_CASE("array<int, 2>") {
-  typedef std::array<int, 2> array_type;
+  using array_type = std::array<int, 2>;
 
   SECTION("toJson") {
     array_type v;

extras/tests/Misc/custom_string.hpp

@@ -8,4 +8,4 @@
 
 struct custom_char_traits : std::char_traits<char> {};
 
-typedef std::basic_string<char, custom_char_traits> custom_string;
+using custom_string = std::basic_string<char, custom_char_traits>;