add missing lib

lib/ArduinoJson/test/JsonObject/size.cpp

@@ -0,0 +1,23 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <string>
+
+TEST_CASE("JsonObject::size()") {
+  DynamicJsonBuffer jb;
+  JsonObject& _object = jb.createObject();
+
+  SECTION("increases when values are added") {
+    _object.set("hello", 42);
+    REQUIRE(1 == _object.size());
+  }
+
+  SECTION("doesn't increase when the smae key is added twice") {
+    _object["hello"] = 1;
+    _object["hello"] = 2;
+    REQUIRE(1 == _object.size());
+  }
+}