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use crate::cli::TestOpts;
use crate::types::{TestDescAndFn, TestId, TestName};
use std::collections::hash_map::DefaultHasher;
use std::hash::Hasher;
use std::time::{SystemTime, UNIX_EPOCH};
pub fn get_shuffle_seed(opts: &TestOpts) -> Option<u64> {
opts.shuffle_seed.or_else(|| {
if opts.shuffle {
Some(
SystemTime::now()
.duration_since(UNIX_EPOCH)
.expect("Failed to get system time")
.as_nanos() as u64,
)
} else {
None
}
})
}
pub fn shuffle_tests(shuffle_seed: u64, tests: &mut [(TestId, TestDescAndFn)]) {
let test_names: Vec<&TestName> = tests.iter().map(|test| &test.1.desc.name).collect();
let test_names_hash = calculate_hash(&test_names);
let mut rng = Rng::new(shuffle_seed, test_names_hash);
shuffle(&mut rng, tests);
}
// `shuffle` is from `rust-analyzer/src/cli/analysis_stats.rs`.
fn shuffle<T>(rng: &mut Rng, slice: &mut [T]) {
for i in 0..slice.len() {
randomize_first(rng, &mut slice[i..]);
}
fn randomize_first<T>(rng: &mut Rng, slice: &mut [T]) {
assert!(!slice.is_empty());
let idx = rng.rand_range(0..slice.len() as u64) as usize;
slice.swap(0, idx);
}
}
struct Rng {
state: u64,
extra: u64,
}
impl Rng {
fn new(seed: u64, extra: u64) -> Self {
Self { state: seed, extra }
}
fn rand_range(&mut self, range: core::ops::Range<u64>) -> u64 {
self.rand_u64() % (range.end - range.start) + range.start
}
fn rand_u64(&mut self) -> u64 {
self.state = calculate_hash(&(self.state, self.extra));
self.state
}
}
// `calculate_hash` is from `core/src/hash/mod.rs`.
fn calculate_hash<T: core::hash::Hash>(t: &T) -> u64 {
let mut s = DefaultHasher::new();
t.hash(&mut s);
s.finish()
}
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