/
check.rs
347 lines (323 loc) · 10.7 KB
/
check.rs
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use crate::{generate::State, prove::Prove, shrink::Shrink, Generate};
use fastrand::Rng;
use std::{
borrow::Cow,
error, fmt,
marker::PhantomData,
num::NonZeroUsize,
panic::{self, AssertUnwindSafe},
sync::atomic::{AtomicUsize, Ordering},
thread::{available_parallelism, scope},
time::{Duration, Instant},
};
#[derive(Clone, Copy, Debug)]
pub struct Shrinks {
/// Maximum number of successful attempts at reducing the 'size' of the input before aborting the shrinking process.
pub accept: usize,
/// Maximum number of failed attempts at reducing the 'size' of the input before aborting the shrinking process.
pub reject: usize,
/// Maximum time spent shrinking.
pub duration: Duration,
}
#[derive(Debug)]
pub struct Checker<'a, G: ?Sized> {
/// A generator that will provide the values and shrinkers for the checking and shrinking processes.
pub generator: &'a G,
/// Maximum number of errors that the results of a `check` call will contain. When it is reached, the checking process aborts.
/// Defaults to 1.
pub errors: usize,
/// Limits the shrinking process.
/// Defaults to a duration limit of 30 seconds.
pub shrinks: Shrinks,
/// Seed for the random number generator used to generate random primitives.
pub seed: Option<u64>,
}
#[derive(Debug)]
pub struct Checks<'a, G: ?Sized, P, F> {
checker: Checker<'a, G>,
random: Rng,
errors: usize,
index: usize,
count: usize,
check: F,
_marker: PhantomData<P>,
}
#[derive(Clone, Debug)]
pub struct Error<T, P> {
/// The generator state that generated the error.
pub state: State,
pub cause: Cause<P>,
pub original: T,
pub shrunk: Option<T>,
pub shrinks: Shrinks,
}
#[derive(Clone, Debug)]
pub enum Cause<P> {
Disprove(P),
Panic(Cow<'static, str>),
Unknown,
}
impl<T, P> Error<T, P> {
pub fn shrunk(&self) -> &T {
self.shrunk.as_ref().unwrap_or(&self.original)
}
}
impl<'a, G: ?Sized> Checker<'a, G> {
pub const fn new(generator: &'a G) -> Self {
Self {
generator,
errors: 1,
shrinks: Shrinks {
accept: usize::MAX,
reject: usize::MAX,
duration: Duration::from_secs(30),
},
seed: None,
}
}
}
impl<G: ?Sized> Clone for Checker<'_, G> {
fn clone(&self) -> Self {
Self {
generator: self.generator,
errors: self.errors,
shrinks: self.shrinks,
seed: self.seed,
}
}
}
impl<'a, G: Generate + ?Sized> Checker<'a, G> {
pub fn check<P: Prove, F: FnMut(&G::Item) -> P>(
&self,
size: f64,
check: F,
) -> Result<G::Item, Error<G::Item, P>> {
next(
self.generator,
State::new(size, self.seed),
self.shrinks,
check,
)
}
pub fn checks<P: Prove, F: FnMut(&G::Item) -> P>(
&self,
count: usize,
check: F,
) -> Checks<'a, G, P, F> {
Checks {
checker: self.clone(),
random: self.seed.map_or_else(Rng::new, Rng::with_seed),
errors: 0,
index: 0,
count,
check,
_marker: PhantomData,
}
}
}
impl<'a, G: Generate + ?Sized + Sync> Checker<'a, G>
where
G::Item: Send,
{
pub fn check_parallel<'b, P: Prove + Send + 'b, F: Fn(&G::Item) -> P + Sync + 'b>(
&'b self,
count: usize,
parallel: Option<usize>,
check: F,
) -> impl Iterator<Item = Result<G::Item, Error<G::Item, P>>> + 'b {
let parallel = match parallel {
Some(parallel) => parallel.max(1),
None => available_parallelism().map_or(1, NonZeroUsize::get),
};
let mut results = Vec::with_capacity(count);
let errors = AtomicUsize::new(0);
let mut random = self.seed.map_or_else(Rng::new, Rng::with_seed);
let capacity = divide_ceiling(count, parallel);
if capacity <= 8 || count < 32 {
batch(
self.generator,
&mut results,
(0, 1, count),
self.shrinks,
(&errors, self.errors),
&mut random,
check,
);
} else {
scope(|scope| {
let mut handles = Vec::with_capacity(parallel - 1);
for offset in 0..parallel - 1 {
let check = ✓
let errors = &errors;
let seed = random.u64(..);
handles.push(scope.spawn(move || {
let mut results = Vec::with_capacity(capacity);
batch(
self.generator,
&mut results,
(offset, parallel, count),
self.shrinks,
(errors, self.errors),
&mut Rng::with_seed(seed),
check,
);
results
}));
}
batch(
self.generator,
&mut results,
(parallel - 1, parallel, count),
self.shrinks,
(&errors, self.errors),
&mut random,
&check,
);
for handle in handles {
results.extend(handle.join().into_iter().flatten());
}
});
}
results.into_iter()
}
}
impl<G: Generate + ?Sized, P: Prove, F: FnMut(&G::Item) -> P> Iterator for Checks<'_, G, P, F> {
type Item = Result<G::Item, Error<G::Item, P>>;
fn next(&mut self) -> Option<Self::Item> {
if self.index >= self.count || self.errors >= self.checker.errors {
None
} else {
let result = next(
self.checker.generator,
State::from_iteration(self.index, self.count, Some(self.random.u64(..))),
self.checker.shrinks,
&mut self.check,
);
self.index += 1;
match result {
Ok(item) if self.errors < self.checker.errors => Some(Ok(item)),
Err(error) if self.errors < self.checker.errors => {
self.errors += 1;
Some(Err(error))
}
_ => None,
}
}
}
}
fn handle<T, P: Prove, F: FnMut(&T) -> P>(item: &T, check: &mut F) -> Option<Cause<P>> {
let error = match panic::catch_unwind(AssertUnwindSafe(|| check(item))) {
Ok(prove) if prove.prove() => return None,
Ok(prove) => return Some(Cause::Disprove(prove)),
Err(error) => error,
};
let error = match error.downcast::<&'static str>() {
Ok(error) => return Some(Cause::Panic(Cow::Borrowed(*error))),
Err(error) => error,
};
let error = match error.downcast::<String>() {
Ok(error) => return Some(Cause::Panic(Cow::Owned(*error))),
Err(error) => error,
};
let error = match error.downcast::<Box<str>>() {
Ok(error) => return Some(Cause::Panic(Cow::Owned(error.to_string()))),
Err(error) => error,
};
match error.downcast::<Cow<'static, str>>() {
Ok(error) => Some(Cause::Panic(*error)),
Err(_) => Some(Cause::Unknown),
}
}
fn next<G: Generate + ?Sized, P: Prove, F: FnMut(&G::Item) -> P>(
generator: &G,
mut state: State,
shrinks: Shrinks,
mut check: F,
) -> Result<G::Item, Error<G::Item, P>> {
let mut outer = generator.generate(&mut state);
let item = outer.item();
let cause = match handle(&item, &mut check) {
Some(cause) => cause,
_ => return Ok(item),
};
let mut error = Error {
state,
cause,
original: item,
shrinks: Shrinks {
accept: 0,
reject: 0,
duration: Duration::ZERO,
},
shrunk: None,
};
let now = Instant::now();
while error.shrinks.reject < shrinks.reject
&& error.shrinks.accept < shrinks.accept
&& error.shrinks.duration < shrinks.duration
{
if let Some(inner) = outer.shrink() {
let item = inner.item();
match handle(&item, &mut check) {
Some(cause) if error.cause == cause => {
error.shrinks.reject = 0;
error.shrinks.accept += 1;
error.shrunk = Some(item);
outer = inner;
}
_ => error.shrinks.reject += 1,
}
error.shrinks.duration = Instant::now() - now;
} else {
break;
}
}
Err(error)
}
type Results<G, P> = Vec<Result<<G as Generate>::Item, Error<<G as Generate>::Item, P>>>;
fn batch<G: Generate + ?Sized, P: Prove, F: Fn(&G::Item) -> P>(
generator: &G,
results: &mut Results<G, P>,
(offset, step, count): (usize, usize, usize),
shrinks: Shrinks,
errors: (&AtomicUsize, usize),
random: &mut Rng,
check: F,
) {
for index in (offset..count).step_by(step) {
let state = State::from_iteration(index, count, Some(random.u64(..)));
match next(generator, state, shrinks, &check) {
Ok(item) if errors.0.load(Ordering::Relaxed) < errors.1 => results.push(Ok(item)),
Err(error) if errors.0.fetch_add(1, Ordering::Relaxed) < errors.1 => {
results.push(Err(error))
}
_ => break,
}
}
}
const fn divide_ceiling(left: usize, right: usize) -> usize {
let value = left / right;
let remain = left % right;
if remain > 0 && right > 0 {
value + 1
} else {
value
}
}
impl<P: Prove> PartialEq for Cause<P> {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
(Self::Disprove(left), Self::Disprove(right)) => left.is(right),
(Self::Panic(left), Self::Panic(right)) => left == right,
(Self::Unknown, Self::Unknown) => true,
_ => false,
}
}
}
impl<P: Prove> Eq for Cause<P> {}
impl<T: fmt::Debug, P: fmt::Debug> fmt::Display for Error<T, P> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(self, f)
}
}
impl<T: fmt::Debug, P: fmt::Debug> error::Error for Error<T, P> {}