Reference-count shared strings

extras/tests/JsonVariant/clear.cpp

@@ -6,6 +6,9 @@
 #include <stdint.h>
 #include <catch.hpp>
 
+using ArduinoJson::detail::sizeofArray;
+using ArduinoJson::detail::sizeofString;
+
 TEST_CASE("JsonVariant::clear()") {
   JsonDocument doc(4096);
   JsonVariant var = doc.to<JsonVariant>();
@@ -23,4 +26,12 @@ TEST_CASE("JsonVariant::clear()") {
 
     REQUIRE(var.isNull() == true);
   }
+
+  SECTION("releases owned string") {
+    var.set(std::string("hello"));
+    REQUIRE(doc.memoryUsage() == sizeofString(5));
+
+    var.clear();
+    REQUIRE(doc.memoryUsage() == 0);
+  }
 }