Update rand to 0.7

Fix some test code accordingly.  Note, this includes fix for the test
code of bitset-fixed.  The test expected the number sequences generated
from the same seed is always the same. It seems the rand 0.7 produces
different sequence for the seed, so change the result value to fit for
rand 0.7.

Author: statiolake

Cargo.toml

@@ -61,9 +61,9 @@ im-rc = "=13.0.0"
 num = "=0.2.0"
 
 # RNG 疑似乱数生成器 (randファミリー)
-rand = "=0.6.5"
-rand_chacha = "=0.1.1"
-rand_pcg = "=0.1.2"
+rand = { version = "=0.7.0", features = ["small_rng"] }
+rand_chacha = "=0.2.1"
+rand_pcg = "=0.2.0"
 
 # 正規表現
 regex = "=1.2.1"

src/main.rs

@@ -246,7 +246,7 @@ fn run_bitset_fixed() {
     use rand::distributions::Uniform;
     use rand::prelude::*;
 
-    let mut rng = StdRng::seed_from_u64(114514);
+    let rng = StdRng::seed_from_u64(114514);
     let dist = Uniform::from(0..2000);
 
     let n = rng
@@ -265,7 +265,7 @@ fn run_bitset_fixed() {
     let ans = ((sum + 1) / 2..).find(|&i| bitset[i]).unwrap();
 
     println!("N = {:?}\nAnswer = {}", n, ans);
-    assert_eq!(ans, 14675);
+    assert_eq!(ans, 13465);
 }
 
 #[test]
@@ -403,6 +403,8 @@ fn test_rand_family() -> UnitResult {
 }
 
 fn calc_mean(rng: &mut impl rand::Rng) -> f64 {
+    // to see `impl Rng for &mut R where R: Rng`, which prevent moving in `rng.sample_iter()`
+    use rand::Rng as _;
     const ITERATIONS: usize = 10000;
 
     // the stardard distribution for f64 generates a random rumber in interval [0, 1)