Add an empty cpp file to detect warnings muted by catch.hpp

test/Misc/CMakeLists.txt

@@ -3,6 +3,7 @@
 # MIT License
 
 add_executable(MiscTests
+    empty.cpp
 	FloatParts.cpp
 	StringWriter.cpp
 	TypeTraits.cpp

test/Misc/empty.cpp

@@ -0,0 +1,7 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+// catch.hpp mutes several warnings, this file allows to detect them
+
+#include "ArduinoJson.h"