Victor Hsieh | 682e64b | 2020-12-15 13:48:22 -0800 | [diff] [blame] | 1 | use rand_core::{RngCore, SeedableRng}; |
| 2 | use rand_xorshift::XorShiftRng; |
| 3 | |
| 4 | #[test] |
| 5 | fn test_xorshift_construction() { |
| 6 | // Test that various construction techniques produce a working RNG. |
| 7 | let seed = [1,2,3,4, 5,6,7,8, 9,10,11,12, 13,14,15,16]; |
| 8 | let mut rng1 = XorShiftRng::from_seed(seed); |
| 9 | assert_eq!(rng1.next_u64(), 4325440999699518727); |
| 10 | |
| 11 | let mut rng2 = XorShiftRng::from_rng(&mut rng1).unwrap(); |
| 12 | // Yes, this makes rng2 a clone of rng1! |
| 13 | assert_eq!(rng1.next_u64(), 15614385950550801700); |
| 14 | assert_eq!(rng2.next_u64(), 15614385950550801700); |
| 15 | } |
| 16 | |
| 17 | #[test] |
| 18 | fn test_xorshift_true_values() { |
| 19 | let seed = [16,15,14,13, 12,11,10,9, 8,7,6,5, 4,3,2,1]; |
| 20 | let mut rng = XorShiftRng::from_seed(seed); |
| 21 | |
| 22 | let mut results = [0u32; 9]; |
| 23 | for i in results.iter_mut() { *i = rng.next_u32(); } |
| 24 | let expected: [u32; 9] = [ |
| 25 | 2081028795, 620940381, 269070770, 16943764, 854422573, 29242889, |
| 26 | 1550291885, 1227154591, 271695242]; |
| 27 | assert_eq!(results, expected); |
| 28 | |
| 29 | let mut results = [0u64; 9]; |
| 30 | for i in results.iter_mut() { *i = rng.next_u64(); } |
| 31 | let expected: [u64; 9] = [ |
| 32 | 9247529084182843387, 8321512596129439293, 14104136531997710878, |
| 33 | 6848554330849612046, 343577296533772213, 17828467390962600268, |
| 34 | 9847333257685787782, 7717352744383350108, 1133407547287910111]; |
| 35 | assert_eq!(results, expected); |
| 36 | |
| 37 | let mut results = [0u8; 32]; |
| 38 | rng.fill_bytes(&mut results); |
| 39 | let expected = [102, 57, 212, 16, 233, 130, 49, 183, |
| 40 | 158, 187, 44, 203, 63, 149, 45, 17, |
| 41 | 117, 129, 131, 160, 70, 121, 158, 155, |
| 42 | 224, 209, 192, 53, 10, 62, 57, 72]; |
| 43 | assert_eq!(results, expected); |
| 44 | } |
| 45 | |
| 46 | #[test] |
| 47 | fn test_xorshift_zero_seed() { |
| 48 | // Xorshift does not work with an all zero seed. |
| 49 | // Assert it does not panic. |
| 50 | let seed = [0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0]; |
| 51 | let mut rng = XorShiftRng::from_seed(seed); |
| 52 | let a = rng.next_u64(); |
| 53 | let b = rng.next_u64(); |
| 54 | assert!(a != 0); |
| 55 | assert!(b != a); |
| 56 | } |
| 57 | |
| 58 | #[test] |
| 59 | fn test_xorshift_clone() { |
| 60 | let seed = [1,2,3,4, 5,5,7,8, 8,7,6,5, 4,3,2,1]; |
| 61 | let mut rng1 = XorShiftRng::from_seed(seed); |
| 62 | let mut rng2 = rng1.clone(); |
| 63 | for _ in 0..16 { |
| 64 | assert_eq!(rng1.next_u64(), rng2.next_u64()); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | #[cfg(feature="serde1")] |
| 69 | #[test] |
| 70 | fn test_xorshift_serde() { |
| 71 | use bincode; |
| 72 | use std::io::{BufWriter, BufReader}; |
| 73 | |
| 74 | let seed = [1,2,3,4, 5,6,7,8, 9,10,11,12, 13,14,15,16]; |
| 75 | let mut rng = XorShiftRng::from_seed(seed); |
| 76 | |
| 77 | let buf: Vec<u8> = Vec::new(); |
| 78 | let mut buf = BufWriter::new(buf); |
| 79 | bincode::serialize_into(&mut buf, &rng).expect("Could not serialize"); |
| 80 | |
| 81 | let buf = buf.into_inner().unwrap(); |
| 82 | let mut read = BufReader::new(&buf[..]); |
| 83 | let mut deserialized: XorShiftRng = bincode::deserialize_from(&mut read) |
| 84 | .expect("Could not deserialize"); |
| 85 | |
| 86 | for _ in 0..16 { |
| 87 | assert_eq!(rng.next_u64(), deserialized.next_u64()); |
| 88 | } |
| 89 | } |