Summary

It seems that random_range() always returns its lower bound. I've checked it with debugger, and it seems that value returned from Rng is for unknown reason replaced with 0, and then forced into range.

Rand 0.9.0, Rust 1.84.1, Windows 11.

Code sample

#[test]
fn gen() {
    let mut rng = StepRng::new(1, 1);
    let res = [
        rng.random_range(1..=6),
        rng.random_range(1..=6),
        rng.random_range(1..=6),
    ];
    assert_eq!(res, [1, 2, 3]);
}

results in

assertion `left == right` failed
  left: [1, 1, 1]
 right: [1, 2, 3]