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//! Tests for the `block` module items
use rand_core::{
SeedableRng,
block::{BlockRng, Generator},
};
const RESULTS_LEN: usize = 16;
#[derive(Debug, Clone)]
struct DummyRng {
counter: u32,
}
impl Generator for DummyRng {
type Output = [u32; RESULTS_LEN];
fn generate(&mut self, output: &mut Self::Output) {
for item in output {
*item = self.counter;
self.counter = self.counter.wrapping_add(3511615421);
}
}
}
impl SeedableRng for DummyRng {
type Seed = [u8; 4];
fn from_seed(seed: Self::Seed) -> Self {
DummyRng {
counter: u32::from_le_bytes(seed),
}
}
}
#[test]
fn blockrng_next_u32_vs_next_u64() {
let mut rng1 = BlockRng::new(DummyRng::from_seed([1, 2, 3, 4]));
let mut rng2 = rng1.clone();
let mut rng3 = rng1.clone();
let mut a = [0; 16];
a[..4].copy_from_slice(&rng1.next_word().to_le_bytes());
a[4..12].copy_from_slice(&rng1.next_u64_from_u32().to_le_bytes());
a[12..].copy_from_slice(&rng1.next_word().to_le_bytes());
let mut b = [0; 16];
b[..4].copy_from_slice(&rng2.next_word().to_le_bytes());
b[4..8].copy_from_slice(&rng2.next_word().to_le_bytes());
b[8..].copy_from_slice(&rng2.next_u64_from_u32().to_le_bytes());
assert_eq!(a, b);
let mut c = [0; 16];
c[..8].copy_from_slice(&rng3.next_u64_from_u32().to_le_bytes());
c[8..12].copy_from_slice(&rng3.next_word().to_le_bytes());
c[12..].copy_from_slice(&rng3.next_word().to_le_bytes());
assert_eq!(a, c);
}
#[test]
fn blockrng_next_u64() {
let mut rng = BlockRng::new(DummyRng::from_seed([1, 2, 3, 4]));
let result_size = RESULTS_LEN;
for _i in 0..result_size / 2 - 1 {
rng.next_u64_from_u32();
}
rng.next_word();
let _ = rng.next_u64_from_u32();
assert_eq!(rng.word_offset(), 1);
}
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