Add mock ESP class

test/emul/Arduino.cpp

@@ -14,3 +14,5 @@ void pinMode(uint8_t pin, uint8_t mode) {}
 int max(int a, int b) {
   return (a > b) ? a : b;
 }
+
+ESPClass ESP;

test/emul/Arduino.h

@@ -24,4 +24,15 @@ void delay(unsigned long ms);
 void delayMicroseconds(unsigned long us);
 int max(int a, int b);
 
+class ESPClass {
+public:
+    size_t getFlashChipSize() {
+        // This is a placeholder for the actual implementation
+        // that retrieves the flash chip size.
+        return 4 * 1024 * 1024; // Example: returning 4MB
+    }
+};
+
+extern ESPClass ESP;
+
 #endif