Fixed naming conflict with "CAPACITY" (issue #839)

test/Misc/conflicts.cpp

@@ -0,0 +1,42 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+// All cores
+#define bit()
+#define constrain()
+#define DEFAULT
+#define DISABLED
+#define HIGH
+#define INPUT
+#define LOW
+#define max()
+#define min()
+#define OUTPUT
+#define round()
+#define sq()
+#define word()
+#define bitRead()
+#define bitSet()
+#define bitClear()
+#define bitWrite()
+#define interrupts()
+#define lowByte()
+#define highByte()
+#define DEC
+#define HEX
+#define OCT
+#define BIN
+#define cbi()
+#define sbi()
+
+// ESP8266
+#define _max()
+#define _min()
+
+// issue #839
+#define BLOCKSIZE
+#define CAPACITY
+
+// catch.hpp mutes several warnings, this file also allows to detect them
+#include "ArduinoJson.h"