Two Argons Communicating over I2C

Firmware
1

I’m using the following sets of code for two Argons connected via I2C:

device 1 code:

void setup() {
  Serial.begin(115200);
  Wire.begin();
}
void loop() {
  Wire.requestFrom(4, 4);
  while(Wire.available()> 0){
    char c = Wire.read();
    Serial.println(c);
  }
  delay(100);
}

Device 2 with code:

void test(){
  Wire.write("test");
}

void setup() {
  Wire.begin(4);
  Wire.onRequest(test); 
}

I had hooked up a pair of photons in this way and had results. But now that I’m using Argons, nothing appears to be getting printed to the SerialPort. Is there some change to I2C between Gen2 and Gen3?