test filesystem sketch

test.ino

#include <LittleFS.h>

#define  CONFIG_FILENAME              F("/wifi_cred.dat")

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);

//  LittleFS.format();
  LittleFS.begin();

  loadConfigData();
}

void loop() {
  // put your main code here, to run repeatedly:

}

void loadConfigData(void)
{
  File file = LittleFS.open(CONFIG_FILENAME, "r");
  Serial.println("LoadWiFiCfgFile ");

  if (file)
  {
    int line = file.read();
    Serial.print((char)line);
    while (line != -1){
      line = file.read();
      Serial.print((char)line);
    }
    file.close();
    Serial.println("\nLOAD OK");
  }
  else
  {
    Serial.println("LOAD failed");
  }
}