Ported test of Gbathree's bug

test/Printers.cpp

@@ -0,0 +1,13 @@
+// Copyright Benoit Blanchon 2014
+// MIT License
+//
+// Arduino JSON library
+// https://github.com/bblanchon/ArduinoJson
+
+#include "Printers.hpp"
+
+std::ostream& ArduinoJson::operator<<(std::ostream& os,
+                                      const ArduinoJson::JsonValue&) {
+  os << "JsonValue";  // TODO
+  return os;
+}