arduino RGB LEDs over serial

const int ledGreenPin = 3;
const int ledBluePin = 4;
int incomingByte;

void setup() {
  // initialize serial communication:
  Serial.begin(9600);
  Serial.print("YOYOYO\n");
  // initialize the LED pin as an output:
  pinMode(ledRedPin, OUTPUT);
  pinMode(ledGreenPin, OUTPUT);
  pinMode(ledBluePin, OUTPUT);
}

void redOn() {
  digitalWrite(ledRedPin, HIGH);
  digitalWrite(ledGreenPin, LOW);
  digitalWrite(ledBluePin, LOW);
}

void greenOn() {
  digitalWrite(ledRedPin, LOW);
  digitalWrite(ledGreenPin, HIGH);
  digitalWrite(ledBluePin, LOW);
}

void blueOn() {
  digitalWrite(ledRedPin, LOW);
  digitalWrite(ledGreenPin, LOW);
  digitalWrite(ledBluePin, HIGH);
}

void testResponse() {
  Serial.print("SUCCESS\n");
}

void loop() {
  // see if there's incoming serial data:
  if (Serial.available() > 0) {
    // read the oldest byte in the serial buffer:
    incomingByte = Serial.read();
    if (incomingByte == 'R') {
	redOn();
    } 
    if (incomingByte == 'G') {
	greenOn();
    }
    if (incomingByte == 'B') {
	blueOn();
    }
    if (incomingByte == 'T') {
	digitalWrite(ledRedPin, HIGH);
	digitalWrite(ledGreenPin, HIGH);
	digitalWrite(ledBluePin, HIGH);
	testResponse();
    }
  }
}