buzz.rs

extern mod std;

fn is_three(num: int) -> bool {
  num % 3 == 0
}

#[test]
fn test_is_three() {
  assert is_three(1) == false;
  assert is_three(3) == true;
}

fn is_five(num: int) -> bool {
  num % 5 == 0
}

#[test]
fn test_is_five() {
  assert is_five(1) == false;
  assert is_five(5) == true;
}

fn is_fifteen(num: int) -> bool {
  num % 15 == 0
}

#[test]
fn test_is_fifteen() {
  assert is_fifteen(1) == false;
  assert is_fifteen(15) == true;
}

fn main() {
  for int::range(0, 100) |num| {
    io::println(
      if is_fifteen(num) { ~"FizzBuzz" }
      else if is_three(num) { ~"Fizz" }
      else if is_five(num) { ~"Buzz" }
      else { int::str(num) }
    );
  }
}

fizz.rs

extern mod std;

fn is_three(num: int) -> bool {
  num % 3 == 0
}

#[test]
fn test_is_three() {
  assert is_three(1) == false;
  assert is_three(3) == true;
}

fn is_five(num: int) -> bool {
  num % 5 == 0
}

#[test]
fn test_is_five() {
  assert is_five(1) == false;
  assert is_five(5) == true;
}

fn is_fifteen(num: int) -> bool {
  num % 15 == 0
}

#[test]
fn test_is_fifteen() {
  assert is_fifteen(1) == false;
  assert is_fifteen(15) == true;
}

fn main() {
  for int::range(0, 100) |num| {
    let answer = 
      if is_fifteen(num){
        ~"FizzBuzz"
      }
      else if is_three(num) {
        ~"Fizz"
      }
      else if is_five(num) {
        ~"Buzz"
      }
      else {
        int::str(num)
      };
    io::println(answer)
  }
}