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// round - rust library (crate)
// GNU licensed, license file can be found at the root of the repository
// Mohamed Hayibor - Copyright 2016

pub fn round(number: f64, rounding: i32) -> f64 {
  let scale: f64 = 10_f64.powi(rounding);
  (number * scale).round() / scale
}

// implementing round_up and round_down with same design pattern
pub fn round_up(number: f64, rounding: i32) -> f64 {
  let scale: f64 = 10_f64.powi(rounding);
  (number * scale).ceil() / scale
}

pub fn round_down(number: f64, rounding: i32) -> f64 {
  let scale: f64 = 10_f64.powi(rounding);
  (number * scale).floor() / scale
}

#[cfg(test)]
mod tests {
  use super::*;
  
  #[test]
  fn test_round() {
    let pi: f64 = std::f64::consts::PI;

    assert_eq!(round(pi, 0), 3.0);
    assert_eq!(round(pi, 1), 3.1);
    assert_eq!(round(pi, 2), 3.14);
    assert_eq!(round(pi, 3), 3.142);
    assert_eq!(round(pi, 4), 3.1416);
    assert_eq!(round(pi, 5), 3.14159);
    assert_eq!(round(pi, 6), 3.141593);
    assert_eq!(round(pi, 7), 3.1415927);
    assert_eq!(round(pi, 8), 3.14159265);
  }

  #[test]
  fn test_round_down() {
    let pi: f64 = std::f64::consts::PI;

    assert_eq!(round_down(pi, 0), 3.0);
    assert_eq!(round_down(pi, 1), 3.1);
    assert_eq!(round_down(pi, 2), 3.14);
    assert_eq!(round_down(pi, 3), 3.141);
    assert_eq!(round_down(pi, 4), 3.1415);
    assert_eq!(round_down(pi, 5), 3.14159);
    assert_eq!(round_down(pi, 6), 3.141592);
    assert_eq!(round_down(pi, 7), 3.1415926);
    assert_eq!(round_down(pi, 8), 3.14159265);
  }

  #[test]
  fn test_round_up() {
    let pi: f64 = std::f64::consts::PI;
    
    assert_eq!(round_up(pi, 0), 4.0);
    assert_eq!(round_up(pi, 1), 3.2);
    assert_eq!(round_up(pi, 2), 3.15);
    assert_eq!(round_up(pi, 3), 3.142);
    assert_eq!(round_up(pi, 4), 3.1416);
    assert_eq!(round_up(pi, 5), 3.14160);
    assert_eq!(round_up(pi, 6), 3.141593);
    assert_eq!(round_up(pi, 7), 3.1415927);
    assert_eq!(round_up(pi, 8), 3.14159266);
  }
}