pub fn trend(prev: f64, current: f64) -> [f64; 2] {
let mut up = 0.0;
let mut down = 0.0;
if prev > current {
down = prev - current;
}
if current > prev {
up = current - prev;
}
[up, down]
}
#[cfg(test)]
mod tests {
use crate::helpers::trend;
#[test]
fn trend_works() {
assert_eq!([50.0, 0.0], trend(100.0, 150.0));
assert_eq!([0.0, 50.0], trend(150.0, 100.0));
assert_eq!([0.0, 0.0], trend(100.0, 100.0));
}
}