Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 2188 insertions, 0 deletions

diff --git a/vendor/rayon/src/iter/test.rs b/vendor/rayon/src/iter/test.rs
new file mode 100644
index 0000000..c72068d
--- /dev/null
+++ b/vendor/rayon/src/iter/test.rs
@@ -0,0 +1,2188 @@
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use super::*;
+use crate::prelude::*;
+use rayon_core::*;
+
+use rand::distributions::Standard;
+use rand::{Rng, SeedableRng};
+use rand_xorshift::XorShiftRng;
+use std::collections::LinkedList;
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
+use std::collections::{BinaryHeap, VecDeque};
+use std::f64;
+use std::fmt::Debug;
+use std::sync::mpsc;
+use std::usize;
+
+fn is_indexed<T: IndexedParallelIterator>(_: T) {}
+
+fn seeded_rng() -> XorShiftRng {
+    let mut seed = <XorShiftRng as SeedableRng>::Seed::default();
+    (0..).zip(seed.as_mut()).for_each(|(i, x)| *x = i);
+    XorShiftRng::from_seed(seed)
+}
+
+#[test]
+fn execute() {
+    let a: Vec<i32> = (0..1024).collect();
+    let mut b = vec![];
+    a.par_iter().map(|&i| i + 1).collect_into_vec(&mut b);
+    let c: Vec<i32> = (0..1024).map(|i| i + 1).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn execute_cloned() {
+    let a: Vec<i32> = (0..1024).collect();
+    let mut b: Vec<i32> = vec![];
+    a.par_iter().cloned().collect_into_vec(&mut b);
+    let c: Vec<i32> = (0..1024).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn execute_range() {
+    let a = 0i32..1024;
+    let mut b = vec![];
+    a.into_par_iter().map(|i| i + 1).collect_into_vec(&mut b);
+    let c: Vec<i32> = (0..1024).map(|i| i + 1).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn execute_unindexed_range() {
+    let a = 0i64..1024;
+    let b: LinkedList<i64> = a.into_par_iter().map(|i| i + 1).collect();
+    let c: LinkedList<i64> = (0..1024).map(|i| i + 1).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn execute_pseudo_indexed_range() {
+    use std::i128::MAX;
+    let range = MAX - 1024..MAX;
+
+    // Given `Some` length, collecting `Vec` will try to act indexed.
+    let a = range.clone().into_par_iter();
+    assert_eq!(a.opt_len(), Some(1024));
+
+    let b: Vec<i128> = a.map(|i| i + 1).collect();
+    let c: Vec<i128> = range.map(|i| i + 1).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn check_map_indexed() {
+    let a = [1, 2, 3];
+    is_indexed(a.par_iter().map(|x| x));
+}
+
+#[test]
+fn map_sum() {
+    let a: Vec<i32> = (0..1024).collect();
+    let r1: i32 = a.par_iter().map(|&i| i + 1).sum();
+    let r2 = a.iter().map(|&i| i + 1).sum();
+    assert_eq!(r1, r2);
+}
+
+#[test]
+fn map_reduce() {
+    let a: Vec<i32> = (0..1024).collect();
+    let r1 = a.par_iter().map(|&i| i + 1).reduce(|| 0, |i, j| i + j);
+    let r2 = a.iter().map(|&i| i + 1).sum();
+    assert_eq!(r1, r2);
+}
+
+#[test]
+fn map_reduce_with() {
+    let a: Vec<i32> = (0..1024).collect();
+    let r1 = a.par_iter().map(|&i| i + 1).reduce_with(|i, j| i + j);
+    let r2 = a.iter().map(|&i| i + 1).sum();
+    assert_eq!(r1, Some(r2));
+}
+
+#[test]
+fn fold_map_reduce() {
+    // Kind of a weird test, but it demonstrates various
+    // transformations that are taking place. Relies on
+    // `with_max_len(1).fold()` being equivalent to `map()`.
+    //
+    // Take each number from 0 to 32 and fold them by appending to a
+    // vector.  Because of `with_max_len(1)`, this will produce 32 vectors,
+    // each with one item.  We then collect all of these into an
+    // individual vector by mapping each into their own vector (so we
+    // have Vec<Vec<i32>>) and then reducing those into a single
+    // vector.
+    let r1 = (0_i32..32)
+        .into_par_iter()
+        .with_max_len(1)
+        .fold(Vec::new, |mut v, e| {
+            v.push(e);
+            v
+        })
+        .map(|v| vec![v])
+        .reduce_with(|mut v_a, v_b| {
+            v_a.extend(v_b);
+            v_a
+        });
+    assert_eq!(
+        r1,
+        Some(vec![
+            vec![0],
+            vec![1],
+            vec![2],
+            vec![3],
+            vec![4],
+            vec![5],
+            vec![6],
+            vec![7],
+            vec![8],
+            vec![9],
+            vec![10],
+            vec![11],
+            vec![12],
+            vec![13],
+            vec![14],
+            vec![15],
+            vec![16],
+            vec![17],
+            vec![18],
+            vec![19],
+            vec![20],
+            vec![21],
+            vec![22],
+            vec![23],
+            vec![24],
+            vec![25],
+            vec![26],
+            vec![27],
+            vec![28],
+            vec![29],
+            vec![30],
+            vec![31]
+        ])
+    );
+}
+
+#[test]
+fn fold_is_full() {
+    let counter = AtomicUsize::new(0);
+    let a = (0_i32..2048)
+        .into_par_iter()
+        .inspect(|_| {
+            counter.fetch_add(1, Ordering::SeqCst);
+        })
+        .fold(|| 0, |a, b| a + b)
+        .find_any(|_| true);
+    assert!(a.is_some());
+    assert!(counter.load(Ordering::SeqCst) < 2048); // should not have visited every single one
+}
+
+#[test]
+fn check_step_by() {
+    let a: Vec<i32> = (0..1024).step_by(2).collect();
+    let b: Vec<i32> = (0..1024).into_par_iter().step_by(2).collect();
+
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_step_by_unaligned() {
+    let a: Vec<i32> = (0..1029).step_by(10).collect();
+    let b: Vec<i32> = (0..1029).into_par_iter().step_by(10).collect();
+
+    assert_eq!(a, b)
+}
+
+#[test]
+fn check_step_by_rev() {
+    let a: Vec<i32> = (0..1024).step_by(2).rev().collect();
+    let b: Vec<i32> = (0..1024).into_par_iter().step_by(2).rev().collect();
+
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_enumerate() {
+    let a: Vec<usize> = (0..1024).rev().collect();
+
+    let mut b = vec![];
+    a.par_iter()
+        .enumerate()
+        .map(|(i, &x)| i + x)
+        .collect_into_vec(&mut b);
+    assert!(b.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_enumerate_rev() {
+    let a: Vec<usize> = (0..1024).rev().collect();
+
+    let mut b = vec![];
+    a.par_iter()
+        .enumerate()
+        .rev()
+        .map(|(i, &x)| i + x)
+        .collect_into_vec(&mut b);
+    assert!(b.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_indices_after_enumerate_split() {
+    let a: Vec<i32> = (0..1024).collect();
+    a.par_iter().enumerate().with_producer(WithProducer);
+
+    struct WithProducer;
+    impl<'a> ProducerCallback<(usize, &'a i32)> for WithProducer {
+        type Output = ();
+        fn callback<P>(self, producer: P)
+        where
+            P: Producer<Item = (usize, &'a i32)>,
+        {
+            let (a, b) = producer.split_at(512);
+            for ((index, value), trusted_index) in a.into_iter().zip(0..) {
+                assert_eq!(index, trusted_index);
+                assert_eq!(index, *value as usize);
+            }
+            for ((index, value), trusted_index) in b.into_iter().zip(512..) {
+                assert_eq!(index, trusted_index);
+                assert_eq!(index, *value as usize);
+            }
+        }
+    }
+}
+
+#[test]
+fn check_increment() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+
+    a.par_iter_mut().enumerate().for_each(|(i, v)| *v += i);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_skip() {
+    let a: Vec<usize> = (0..1024).collect();
+
+    let mut v1 = Vec::new();
+    a.par_iter().skip(16).collect_into_vec(&mut v1);
+    let v2 = a.iter().skip(16).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+
+    let mut v1 = Vec::new();
+    a.par_iter().skip(2048).collect_into_vec(&mut v1);
+    let v2 = a.iter().skip(2048).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+
+    let mut v1 = Vec::new();
+    a.par_iter().skip(0).collect_into_vec(&mut v1);
+    let v2 = a.iter().skip(0).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+
+    // Check that the skipped elements side effects are executed
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    let num = AtomicUsize::new(0);
+    a.par_iter()
+        .map(|&n| num.fetch_add(n, Ordering::Relaxed))
+        .skip(512)
+        .count();
+    assert_eq!(num.load(Ordering::Relaxed), a.iter().sum::<usize>());
+}
+
+#[test]
+fn check_take() {
+    let a: Vec<usize> = (0..1024).collect();
+
+    let mut v1 = Vec::new();
+    a.par_iter().take(16).collect_into_vec(&mut v1);
+    let v2 = a.iter().take(16).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+
+    let mut v1 = Vec::new();
+    a.par_iter().take(2048).collect_into_vec(&mut v1);
+    let v2 = a.iter().take(2048).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+
+    let mut v1 = Vec::new();
+    a.par_iter().take(0).collect_into_vec(&mut v1);
+    let v2 = a.iter().take(0).collect::<Vec<_>>();
+    assert_eq!(v1, v2);
+}
+
+#[test]
+fn check_inspect() {
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    let a = AtomicUsize::new(0);
+    let b: usize = (0_usize..1024)
+        .into_par_iter()
+        .inspect(|&i| {
+            a.fetch_add(i, Ordering::Relaxed);
+        })
+        .sum();
+
+    assert_eq!(a.load(Ordering::Relaxed), b);
+}
+
+#[test]
+fn check_move() {
+    let a = vec![vec![1, 2, 3]];
+    let ptr = a[0].as_ptr();
+
+    let mut b = vec![];
+    a.into_par_iter().collect_into_vec(&mut b);
+
+    // a simple move means the inner vec will be completely unchanged
+    assert_eq!(ptr, b[0].as_ptr());
+}
+
+#[test]
+fn check_drops() {
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    let c = AtomicUsize::new(0);
+    let a = vec![DropCounter(&c); 10];
+
+    let mut b = vec![];
+    a.clone().into_par_iter().collect_into_vec(&mut b);
+    assert_eq!(c.load(Ordering::Relaxed), 0);
+
+    b.into_par_iter();
+    assert_eq!(c.load(Ordering::Relaxed), 10);
+
+    a.into_par_iter().with_producer(Partial);
+    assert_eq!(c.load(Ordering::Relaxed), 20);
+
+    #[derive(Clone)]
+    struct DropCounter<'a>(&'a AtomicUsize);
+    impl<'a> Drop for DropCounter<'a> {
+        fn drop(&mut self) {
+            self.0.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+
+    struct Partial;
+    impl<'a> ProducerCallback<DropCounter<'a>> for Partial {
+        type Output = ();
+        fn callback<P>(self, producer: P)
+        where
+            P: Producer<Item = DropCounter<'a>>,
+        {
+            let (a, _) = producer.split_at(5);
+            a.into_iter().next();
+        }
+    }
+}
+
+#[test]
+fn check_slice_indexed() {
+    let a = vec![1, 2, 3];
+    is_indexed(a.par_iter());
+}
+
+#[test]
+fn check_slice_mut_indexed() {
+    let mut a = vec![1, 2, 3];
+    is_indexed(a.par_iter_mut());
+}
+
+#[test]
+fn check_vec_indexed() {
+    let a = vec![1, 2, 3];
+    is_indexed(a.into_par_iter());
+}
+
+#[test]
+fn check_range_indexed() {
+    is_indexed((1..5).into_par_iter());
+}
+
+#[test]
+fn check_cmp_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (0..1024).into_par_iter();
+
+    let result = a.cmp(b);
+
+    assert!(result == ::std::cmp::Ordering::Equal);
+}
+
+#[test]
+fn check_cmp_to_seq() {
+    assert_eq!(
+        (0..1024).into_par_iter().cmp(0..1024),
+        (0..1024).cmp(0..1024)
+    );
+}
+
+#[test]
+fn check_cmp_rng_to_seq() {
+    let mut rng = seeded_rng();
+    let rng = &mut rng;
+    let a: Vec<i32> = rng.sample_iter(&Standard).take(1024).collect();
+    let b: Vec<i32> = rng.sample_iter(&Standard).take(1024).collect();
+    for i in 0..a.len() {
+        let par_result = a[i..].par_iter().cmp(b[i..].par_iter());
+        let seq_result = a[i..].iter().cmp(b[i..].iter());
+
+        assert_eq!(par_result, seq_result);
+    }
+}
+
+#[test]
+fn check_cmp_lt_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (1..1024).into_par_iter();
+
+    let result = a.cmp(b);
+
+    assert!(result == ::std::cmp::Ordering::Less);
+}
+
+#[test]
+fn check_cmp_lt_to_seq() {
+    assert_eq!(
+        (0..1024).into_par_iter().cmp(1..1024),
+        (0..1024).cmp(1..1024)
+    )
+}
+
+#[test]
+fn check_cmp_gt_direct() {
+    let a = (1..1024).into_par_iter();
+    let b = (0..1024).into_par_iter();
+
+    let result = a.cmp(b);
+
+    assert!(result == ::std::cmp::Ordering::Greater);
+}
+
+#[test]
+fn check_cmp_gt_to_seq() {
+    assert_eq!(
+        (1..1024).into_par_iter().cmp(0..1024),
+        (1..1024).cmp(0..1024)
+    )
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn check_cmp_short_circuit() {
+    // We only use a single thread in order to make the short-circuit behavior deterministic.
+    let pool = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+
+    let a = vec![0; 1024];
+    let mut b = a.clone();
+    b[42] = 1;
+
+    pool.install(|| {
+        let expected = ::std::cmp::Ordering::Less;
+        assert_eq!(a.par_iter().cmp(&b), expected);
+
+        for len in 1..10 {
+            let counter = AtomicUsize::new(0);
+            let result = a
+                .par_iter()
+                .with_max_len(len)
+                .inspect(|_| {
+                    counter.fetch_add(1, Ordering::SeqCst);
+                })
+                .cmp(&b);
+            assert_eq!(result, expected);
+            // should not have visited every single one
+            assert!(counter.into_inner() < a.len());
+        }
+    });
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn check_partial_cmp_short_circuit() {
+    // We only use a single thread to make the short-circuit behavior deterministic.
+    let pool = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+
+    let a = vec![0; 1024];
+    let mut b = a.clone();
+    b[42] = 1;
+
+    pool.install(|| {
+        let expected = Some(::std::cmp::Ordering::Less);
+        assert_eq!(a.par_iter().partial_cmp(&b), expected);
+
+        for len in 1..10 {
+            let counter = AtomicUsize::new(0);
+            let result = a
+                .par_iter()
+                .with_max_len(len)
+                .inspect(|_| {
+                    counter.fetch_add(1, Ordering::SeqCst);
+                })
+                .partial_cmp(&b);
+            assert_eq!(result, expected);
+            // should not have visited every single one
+            assert!(counter.into_inner() < a.len());
+        }
+    });
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn check_partial_cmp_nan_short_circuit() {
+    // We only use a single thread to make the short-circuit behavior deterministic.
+    let pool = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+
+    let a = vec![0.0; 1024];
+    let mut b = a.clone();
+    b[42] = f64::NAN;
+
+    pool.install(|| {
+        let expected = None;
+        assert_eq!(a.par_iter().partial_cmp(&b), expected);
+
+        for len in 1..10 {
+            let counter = AtomicUsize::new(0);
+            let result = a
+                .par_iter()
+                .with_max_len(len)
+                .inspect(|_| {
+                    counter.fetch_add(1, Ordering::SeqCst);
+                })
+                .partial_cmp(&b);
+            assert_eq!(result, expected);
+            // should not have visited every single one
+            assert!(counter.into_inner() < a.len());
+        }
+    });
+}
+
+#[test]
+fn check_partial_cmp_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (0..1024).into_par_iter();
+
+    let result = a.partial_cmp(b);
+
+    assert!(result == Some(::std::cmp::Ordering::Equal));
+}
+
+#[test]
+fn check_partial_cmp_to_seq() {
+    let par_result = (0..1024).into_par_iter().partial_cmp(0..1024);
+    let seq_result = (0..1024).partial_cmp(0..1024);
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_partial_cmp_rng_to_seq() {
+    let mut rng = seeded_rng();
+    let rng = &mut rng;
+    let a: Vec<i32> = rng.sample_iter(&Standard).take(1024).collect();
+    let b: Vec<i32> = rng.sample_iter(&Standard).take(1024).collect();
+    for i in 0..a.len() {
+        let par_result = a[i..].par_iter().partial_cmp(b[i..].par_iter());
+        let seq_result = a[i..].iter().partial_cmp(b[i..].iter());
+
+        assert_eq!(par_result, seq_result);
+    }
+}
+
+#[test]
+fn check_partial_cmp_lt_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (1..1024).into_par_iter();
+
+    let result = a.partial_cmp(b);
+
+    assert!(result == Some(::std::cmp::Ordering::Less));
+}
+
+#[test]
+fn check_partial_cmp_lt_to_seq() {
+    let par_result = (0..1024).into_par_iter().partial_cmp(1..1024);
+    let seq_result = (0..1024).partial_cmp(1..1024);
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_partial_cmp_gt_direct() {
+    let a = (1..1024).into_par_iter();
+    let b = (0..1024).into_par_iter();
+
+    let result = a.partial_cmp(b);
+
+    assert!(result == Some(::std::cmp::Ordering::Greater));
+}
+
+#[test]
+fn check_partial_cmp_gt_to_seq() {
+    let par_result = (1..1024).into_par_iter().partial_cmp(0..1024);
+    let seq_result = (1..1024).partial_cmp(0..1024);
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_partial_cmp_none_direct() {
+    let a = vec![f64::NAN, 0.0];
+    let b = vec![0.0, 1.0];
+
+    let result = a.par_iter().partial_cmp(b.par_iter());
+
+    assert!(result == None);
+}
+
+#[test]
+fn check_partial_cmp_none_to_seq() {
+    let a = vec![f64::NAN, 0.0];
+    let b = vec![0.0, 1.0];
+
+    let par_result = a.par_iter().partial_cmp(b.par_iter());
+    let seq_result = a.iter().partial_cmp(b.iter());
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_partial_cmp_late_nan_direct() {
+    let a = vec![0.0, f64::NAN];
+    let b = vec![1.0, 1.0];
+
+    let result = a.par_iter().partial_cmp(b.par_iter());
+
+    assert!(result == Some(::std::cmp::Ordering::Less));
+}
+
+#[test]
+fn check_partial_cmp_late_nane_to_seq() {
+    let a = vec![0.0, f64::NAN];
+    let b = vec![1.0, 1.0];
+
+    let par_result = a.par_iter().partial_cmp(b.par_iter());
+    let seq_result = a.iter().partial_cmp(b.iter());
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_cmp_lengths() {
+    // comparisons should consider length if they are otherwise equal
+    let a = vec![0; 1024];
+    let b = vec![0; 1025];
+
+    assert_eq!(a.par_iter().cmp(&b), a.iter().cmp(&b));
+    assert_eq!(a.par_iter().partial_cmp(&b), a.iter().partial_cmp(&b));
+}
+
+#[test]
+fn check_eq_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (0..1024).into_par_iter();
+
+    let result = a.eq(b);
+
+    assert!(result);
+}
+
+#[test]
+fn check_eq_to_seq() {
+    let par_result = (0..1024).into_par_iter().eq((0..1024).into_par_iter());
+    let seq_result = (0..1024).eq(0..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_ne_direct() {
+    let a = (0..1024).into_par_iter();
+    let b = (1..1024).into_par_iter();
+
+    let result = a.ne(b);
+
+    assert!(result);
+}
+
+#[test]
+fn check_ne_to_seq() {
+    let par_result = (0..1024).into_par_iter().ne((1..1025).into_par_iter());
+    let seq_result = (0..1024).ne(1..1025);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_ne_lengths() {
+    // equality should consider length too
+    let a = vec![0; 1024];
+    let b = vec![0; 1025];
+
+    assert_eq!(a.par_iter().eq(&b), a.iter().eq(&b));
+    assert_eq!(a.par_iter().ne(&b), a.iter().ne(&b));
+}
+
+#[test]
+fn check_lt_direct() {
+    assert!((0..1024).into_par_iter().lt(1..1024));
+    assert!(!(1..1024).into_par_iter().lt(0..1024));
+}
+
+#[test]
+fn check_lt_to_seq() {
+    let par_result = (0..1024).into_par_iter().lt((1..1024).into_par_iter());
+    let seq_result = (0..1024).lt(1..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_le_equal_direct() {
+    assert!((0..1024).into_par_iter().le((0..1024).into_par_iter()));
+}
+
+#[test]
+fn check_le_equal_to_seq() {
+    let par_result = (0..1024).into_par_iter().le((0..1024).into_par_iter());
+    let seq_result = (0..1024).le(0..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_le_less_direct() {
+    assert!((0..1024).into_par_iter().le((1..1024).into_par_iter()));
+}
+
+#[test]
+fn check_le_less_to_seq() {
+    let par_result = (0..1024).into_par_iter().le((1..1024).into_par_iter());
+    let seq_result = (0..1024).le(1..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_gt_direct() {
+    assert!((1..1024).into_par_iter().gt((0..1024).into_par_iter()));
+}
+
+#[test]
+fn check_gt_to_seq() {
+    let par_result = (1..1024).into_par_iter().gt((0..1024).into_par_iter());
+    let seq_result = (1..1024).gt(0..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_ge_equal_direct() {
+    assert!((0..1024).into_par_iter().ge((0..1024).into_par_iter()));
+}
+
+#[test]
+fn check_ge_equal_to_seq() {
+    let par_result = (0..1024).into_par_iter().ge((0..1024).into_par_iter());
+    let seq_result = (0..1024).ge(0..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_ge_greater_direct() {
+    assert!((1..1024).into_par_iter().ge((0..1024).into_par_iter()));
+}
+
+#[test]
+fn check_ge_greater_to_seq() {
+    let par_result = (1..1024).into_par_iter().ge((0..1024).into_par_iter());
+    let seq_result = (1..1024).ge(0..1024);
+
+    assert_eq!(par_result, seq_result);
+}
+
+#[test]
+fn check_zip() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+    let b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter_mut().zip(&b[..]).for_each(|(a, &b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_zip_into_par_iter() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+    let b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter_mut()
+        .zip(&b) // here we rely on &b iterating over &usize
+        .for_each(|(a, &b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_zip_into_mut_par_iter() {
+    let a: Vec<usize> = (0..1024).rev().collect();
+    let mut b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter().zip(&mut b).for_each(|(&a, b)| *b += a);
+
+    assert!(b.iter().all(|&x| x == b.len() - 1));
+}
+
+#[test]
+fn check_zip_range() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+
+    a.par_iter_mut()
+        .zip(0usize..1024)
+        .for_each(|(a, b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_zip_eq() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+    let b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter_mut().zip_eq(&b[..]).for_each(|(a, &b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_zip_eq_into_par_iter() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+    let b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter_mut()
+        .zip_eq(&b) // here we rely on &b iterating over &usize
+        .for_each(|(a, &b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_zip_eq_into_mut_par_iter() {
+    let a: Vec<usize> = (0..1024).rev().collect();
+    let mut b: Vec<usize> = (0..1024).collect();
+
+    a.par_iter().zip_eq(&mut b).for_each(|(&a, b)| *b += a);
+
+    assert!(b.iter().all(|&x| x == b.len() - 1));
+}
+
+#[test]
+fn check_zip_eq_range() {
+    let mut a: Vec<usize> = (0..1024).rev().collect();
+
+    a.par_iter_mut()
+        .zip_eq(0usize..1024)
+        .for_each(|(a, b)| *a += b);
+
+    assert!(a.iter().all(|&x| x == a.len() - 1));
+}
+
+#[test]
+fn check_sum_filtered_ints() {
+    let a: Vec<i32> = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let par_sum_evens: i32 = a.par_iter().filter(|&x| (x & 1) == 0).sum();
+    let seq_sum_evens = a.iter().filter(|&x| (x & 1) == 0).sum();
+    assert_eq!(par_sum_evens, seq_sum_evens);
+}
+
+#[test]
+fn check_sum_filtermap_ints() {
+    let a: Vec<i32> = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let par_sum_evens: u32 = a
+        .par_iter()
+        .filter_map(|&x| if (x & 1) == 0 { Some(x as u32) } else { None })
+        .sum();
+    let seq_sum_evens = a
+        .iter()
+        .filter_map(|&x| if (x & 1) == 0 { Some(x as u32) } else { None })
+        .sum();
+    assert_eq!(par_sum_evens, seq_sum_evens);
+}
+
+#[test]
+fn check_flat_map_nested_ranges() {
+    // FIXME -- why are precise type hints required on the integers here?
+
+    let v: i32 = (0_i32..10)
+        .into_par_iter()
+        .flat_map(|i| (0_i32..10).into_par_iter().map(move |j| (i, j)))
+        .map(|(i, j)| i * j)
+        .sum();
+
+    let w = (0_i32..10)
+        .flat_map(|i| (0_i32..10).map(move |j| (i, j)))
+        .map(|(i, j)| i * j)
+        .sum();
+
+    assert_eq!(v, w);
+}
+
+#[test]
+fn check_empty_flat_map_sum() {
+    let a: Vec<i32> = (0..1024).collect();
+    let empty = &a[..0];
+
+    // empty on the inside
+    let b: i32 = a.par_iter().flat_map(|_| empty).sum();
+    assert_eq!(b, 0);
+
+    // empty on the outside
+    let c: i32 = empty.par_iter().flat_map(|_| a.par_iter()).sum();
+    assert_eq!(c, 0);
+}
+
+#[test]
+fn check_flatten_vec() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: Vec<Vec<i32>> = vec![a.clone(), a.clone(), a.clone(), a.clone()];
+    let c: Vec<i32> = b.par_iter().flatten().cloned().collect();
+    let mut d = a.clone();
+    d.extend(&a);
+    d.extend(&a);
+    d.extend(&a);
+
+    assert_eq!(d, c);
+}
+
+#[test]
+fn check_flatten_vec_empty() {
+    let a: Vec<Vec<i32>> = vec![vec![]];
+    let b: Vec<i32> = a.par_iter().flatten().cloned().collect();
+
+    assert_eq!(vec![] as Vec<i32>, b);
+}
+
+#[test]
+fn check_slice_split() {
+    let v: Vec<_> = (0..1000).collect();
+    for m in 1..100 {
+        let a: Vec<_> = v.split(|x| x % m == 0).collect();
+        let b: Vec<_> = v.par_split(|x| x % m == 0).collect();
+        assert_eq!(a, b);
+    }
+
+    // same as std::slice::split() examples
+    let slice = [10, 40, 33, 20];
+    let v: Vec<_> = slice.par_split(|num| num % 3 == 0).collect();
+    assert_eq!(v, &[&slice[..2], &slice[3..]]);
+
+    let slice = [10, 40, 33];
+    let v: Vec<_> = slice.par_split(|num| num % 3 == 0).collect();
+    assert_eq!(v, &[&slice[..2], &slice[..0]]);
+
+    let slice = [10, 6, 33, 20];
+    let v: Vec<_> = slice.par_split(|num| num % 3 == 0).collect();
+    assert_eq!(v, &[&slice[..1], &slice[..0], &slice[3..]]);
+}
+
+#[test]
+fn check_slice_split_mut() {
+    let mut v1: Vec<_> = (0..1000).collect();
+    let mut v2 = v1.clone();
+    for m in 1..100 {
+        let a: Vec<_> = v1.split_mut(|x| x % m == 0).collect();
+        let b: Vec<_> = v2.par_split_mut(|x| x % m == 0).collect();
+        assert_eq!(a, b);
+    }
+
+    // same as std::slice::split_mut() example
+    let mut v = [10, 40, 30, 20, 60, 50];
+    v.par_split_mut(|num| num % 3 == 0).for_each(|group| {
+        group[0] = 1;
+    });
+    assert_eq!(v, [1, 40, 30, 1, 60, 1]);
+}
+
+#[test]
+fn check_chunks() {
+    let a: Vec<i32> = vec![1, 5, 10, 4, 100, 3, 1000, 2, 10000, 1];
+    let par_sum_product_pairs: i32 = a.par_chunks(2).map(|c| c.iter().product::<i32>()).sum();
+    let seq_sum_product_pairs = a.chunks(2).map(|c| c.iter().product::<i32>()).sum();
+    assert_eq!(par_sum_product_pairs, 12345);
+    assert_eq!(par_sum_product_pairs, seq_sum_product_pairs);
+
+    let par_sum_product_triples: i32 = a.par_chunks(3).map(|c| c.iter().product::<i32>()).sum();
+    let seq_sum_product_triples = a.chunks(3).map(|c| c.iter().product::<i32>()).sum();
+    assert_eq!(par_sum_product_triples, 5_0 + 12_00 + 20_000_000 + 1);
+    assert_eq!(par_sum_product_triples, seq_sum_product_triples);
+}
+
+#[test]
+fn check_chunks_mut() {
+    let mut a: Vec<i32> = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let mut b: Vec<i32> = a.clone();
+    a.par_chunks_mut(2).for_each(|c| c[0] = c.iter().sum());
+    b.chunks_mut(2).for_each(|c| c[0] = c.iter().sum());
+    assert_eq!(a, &[3, 2, 7, 4, 11, 6, 15, 8, 19, 10]);
+    assert_eq!(a, b);
+
+    let mut a: Vec<i32> = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let mut b: Vec<i32> = a.clone();
+    a.par_chunks_mut(3).for_each(|c| c[0] = c.iter().sum());
+    b.chunks_mut(3).for_each(|c| c[0] = c.iter().sum());
+    assert_eq!(a, &[6, 2, 3, 15, 5, 6, 24, 8, 9, 10]);
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_windows() {
+    let a: Vec<i32> = (0..1024).collect();
+    let par: Vec<_> = a.par_windows(2).collect();
+    let seq: Vec<_> = a.windows(2).collect();
+    assert_eq!(par, seq);
+
+    let par: Vec<_> = a.par_windows(100).collect();
+    let seq: Vec<_> = a.windows(100).collect();
+    assert_eq!(par, seq);
+
+    let par: Vec<_> = a.par_windows(1_000_000).collect();
+    let seq: Vec<_> = a.windows(1_000_000).collect();
+    assert_eq!(par, seq);
+
+    let par: Vec<_> = a
+        .par_windows(2)
+        .chain(a.par_windows(1_000_000))
+        .zip(a.par_windows(2))
+        .collect();
+    let seq: Vec<_> = a
+        .windows(2)
+        .chain(a.windows(1_000_000))
+        .zip(a.windows(2))
+        .collect();
+    assert_eq!(par, seq);
+}
+
+#[test]
+fn check_options() {
+    let mut a = vec![None, Some(1), None, None, Some(2), Some(4)];
+
+    assert_eq!(7, a.par_iter().flat_map(|opt| opt).sum::<i32>());
+    assert_eq!(7, a.par_iter().flat_map(|opt| opt).sum::<i32>());
+
+    a.par_iter_mut()
+        .flat_map(|opt| opt)
+        .for_each(|x| *x = *x * *x);
+
+    assert_eq!(21, a.into_par_iter().flat_map(|opt| opt).sum::<i32>());
+}
+
+#[test]
+fn check_results() {
+    let mut a = vec![Err(()), Ok(1i32), Err(()), Err(()), Ok(2), Ok(4)];
+
+    assert_eq!(7, a.par_iter().flat_map(|res| res).sum::<i32>());
+
+    assert_eq!(Err::<i32, ()>(()), a.par_iter().cloned().sum());
+    assert_eq!(Ok(7), a.par_iter().cloned().filter(Result::is_ok).sum());
+
+    assert_eq!(Err::<i32, ()>(()), a.par_iter().cloned().product());
+    assert_eq!(Ok(8), a.par_iter().cloned().filter(Result::is_ok).product());
+
+    a.par_iter_mut()
+        .flat_map(|res| res)
+        .for_each(|x| *x = *x * *x);
+
+    assert_eq!(21, a.into_par_iter().flat_map(|res| res).sum::<i32>());
+}
+
+#[test]
+fn check_binary_heap() {
+    use std::collections::BinaryHeap;
+
+    let a: BinaryHeap<i32> = (0..10).collect();
+
+    assert_eq!(45, a.par_iter().sum::<i32>());
+    assert_eq!(45, a.into_par_iter().sum::<i32>());
+}
+
+#[test]
+fn check_btree_map() {
+    use std::collections::BTreeMap;
+
+    let mut a: BTreeMap<i32, i32> = (0..10).map(|i| (i, -i)).collect();
+
+    assert_eq!(45, a.par_iter().map(|(&k, _)| k).sum::<i32>());
+    assert_eq!(-45, a.par_iter().map(|(_, &v)| v).sum::<i32>());
+
+    a.par_iter_mut().for_each(|(k, v)| *v += *k);
+
+    assert_eq!(0, a.into_par_iter().map(|(_, v)| v).sum::<i32>());
+}
+
+#[test]
+fn check_btree_set() {
+    use std::collections::BTreeSet;
+
+    let a: BTreeSet<i32> = (0..10).collect();
+
+    assert_eq!(45, a.par_iter().sum::<i32>());
+    assert_eq!(45, a.into_par_iter().sum::<i32>());
+}
+
+#[test]
+fn check_hash_map() {
+    use std::collections::HashMap;
+
+    let mut a: HashMap<i32, i32> = (0..10).map(|i| (i, -i)).collect();
+
+    assert_eq!(45, a.par_iter().map(|(&k, _)| k).sum::<i32>());
+    assert_eq!(-45, a.par_iter().map(|(_, &v)| v).sum::<i32>());
+
+    a.par_iter_mut().for_each(|(k, v)| *v += *k);
+
+    assert_eq!(0, a.into_par_iter().map(|(_, v)| v).sum::<i32>());
+}
+
+#[test]
+fn check_hash_set() {
+    use std::collections::HashSet;
+
+    let a: HashSet<i32> = (0..10).collect();
+
+    assert_eq!(45, a.par_iter().sum::<i32>());
+    assert_eq!(45, a.into_par_iter().sum::<i32>());
+}
+
+#[test]
+fn check_linked_list() {
+    use std::collections::LinkedList;
+
+    let mut a: LinkedList<i32> = (0..10).collect();
+
+    assert_eq!(45, a.par_iter().sum::<i32>());
+
+    a.par_iter_mut().for_each(|x| *x = -*x);
+
+    assert_eq!(-45, a.into_par_iter().sum::<i32>());
+}
+
+#[test]
+fn check_vec_deque() {
+    use std::collections::VecDeque;
+
+    let mut a: VecDeque<i32> = (0..10).collect();
+
+    // try to get it to wrap around
+    a.drain(..5);
+    a.extend(0..5);
+
+    assert_eq!(45, a.par_iter().sum::<i32>());
+
+    a.par_iter_mut().for_each(|x| *x = -*x);
+
+    assert_eq!(-45, a.into_par_iter().sum::<i32>());
+}
+
+#[test]
+fn check_chain() {
+    let mut res = vec![];
+
+    // stays indexed in the face of madness
+    Some(0)
+        .into_par_iter()
+        .chain(Ok::<_, ()>(1))
+        .chain(1..4)
+        .chain(Err("huh?"))
+        .chain(None)
+        .chain(vec![5, 8, 13])
+        .map(|x| (x as u8 + b'a') as char)
+        .chain(vec!['x', 'y', 'z'])
+        .zip((0i32..1000).into_par_iter().map(|x| -x))
+        .enumerate()
+        .map(|(a, (b, c))| (a, b, c))
+        .chain(None)
+        .collect_into_vec(&mut res);
+
+    assert_eq!(
+        res,
+        vec![
+            (0, 'a', 0),
+            (1, 'b', -1),
+            (2, 'b', -2),
+            (3, 'c', -3),
+            (4, 'd', -4),
+            (5, 'f', -5),
+            (6, 'i', -6),
+            (7, 'n', -7),
+            (8, 'x', -8),
+            (9, 'y', -9),
+            (10, 'z', -10)
+        ]
+    );
+
+    // unindexed is ok too
+    let res: Vec<i32> = Some(1i32)
+        .into_par_iter()
+        .chain(
+            (2i32..4)
+                .into_par_iter()
+                .chain(vec![5, 6, 7, 8, 9])
+                .chain(Some((10, 100)).into_par_iter().flat_map(|(a, b)| a..b))
+                .filter(|x| x & 1 == 1),
+        )
+        .collect();
+    let other: Vec<i32> = (0..100).filter(|x| x & 1 == 1).collect();
+    assert_eq!(res, other);
+
+    // chain collect is ok with the "fake" specialization
+    let res: Vec<i32> = Some(1i32).into_par_iter().chain(None).collect();
+    assert_eq!(res, &[1]);
+}
+
+#[test]
+fn check_count() {
+    let c0 = (0_u32..24 * 1024).filter(|i| i % 2 == 0).count();
+    let c1 = (0_u32..24 * 1024)
+        .into_par_iter()
+        .filter(|i| i % 2 == 0)
+        .count();
+    assert_eq!(c0, c1);
+}
+
+#[test]
+fn find_any() {
+    let a: Vec<i32> = (0..1024).collect();
+
+    assert!(a.par_iter().find_any(|&&x| x % 42 == 41).is_some());
+    assert_eq!(
+        a.par_iter().find_any(|&&x| x % 19 == 1 && x % 53 == 0),
+        Some(&742_i32)
+    );
+    assert_eq!(a.par_iter().find_any(|&&x| x < 0), None);
+
+    assert!(a.par_iter().position_any(|&x| x % 42 == 41).is_some());
+    assert_eq!(
+        a.par_iter().position_any(|&x| x % 19 == 1 && x % 53 == 0),
+        Some(742_usize)
+    );
+    assert_eq!(a.par_iter().position_any(|&x| x < 0), None);
+
+    assert!(a.par_iter().any(|&x| x > 1000));
+    assert!(!a.par_iter().any(|&x| x < 0));
+
+    assert!(!a.par_iter().all(|&x| x > 1000));
+    assert!(a.par_iter().all(|&x| x >= 0));
+}
+
+#[test]
+fn find_first_or_last() {
+    let a: Vec<i32> = (0..1024).collect();
+
+    assert_eq!(a.par_iter().find_first(|&&x| x % 42 == 41), Some(&41_i32));
+    assert_eq!(
+        a.par_iter().find_first(|&&x| x % 19 == 1 && x % 53 == 0),
+        Some(&742_i32)
+    );
+    assert_eq!(a.par_iter().find_first(|&&x| x < 0), None);
+
+    assert_eq!(
+        a.par_iter().position_first(|&x| x % 42 == 41),
+        Some(41_usize)
+    );
+    assert_eq!(
+        a.par_iter().position_first(|&x| x % 19 == 1 && x % 53 == 0),
+        Some(742_usize)
+    );
+    assert_eq!(a.par_iter().position_first(|&x| x < 0), None);
+
+    assert_eq!(a.par_iter().find_last(|&&x| x % 42 == 41), Some(&1007_i32));
+    assert_eq!(
+        a.par_iter().find_last(|&&x| x % 19 == 1 && x % 53 == 0),
+        Some(&742_i32)
+    );
+    assert_eq!(a.par_iter().find_last(|&&x| x < 0), None);
+
+    assert_eq!(
+        a.par_iter().position_last(|&x| x % 42 == 41),
+        Some(1007_usize)
+    );
+    assert_eq!(
+        a.par_iter().position_last(|&x| x % 19 == 1 && x % 53 == 0),
+        Some(742_usize)
+    );
+    assert_eq!(a.par_iter().position_last(|&x| x < 0), None);
+}
+
+#[test]
+fn find_map_first_or_last_or_any() {
+    let mut a: Vec<i32> = vec![];
+
+    assert!(a.par_iter().find_map_any(half_if_positive).is_none());
+    assert!(a.par_iter().find_map_first(half_if_positive).is_none());
+    assert!(a.par_iter().find_map_last(half_if_positive).is_none());
+
+    a = (-1024..-3).collect();
+
+    assert!(a.par_iter().find_map_any(half_if_positive).is_none());
+    assert!(a.par_iter().find_map_first(half_if_positive).is_none());
+    assert!(a.par_iter().find_map_last(half_if_positive).is_none());
+
+    assert!(a.par_iter().find_map_any(half_if_negative).is_some());
+    assert_eq!(
+        a.par_iter().find_map_first(half_if_negative),
+        Some(-512_i32)
+    );
+    assert_eq!(a.par_iter().find_map_last(half_if_negative), Some(-2_i32));
+
+    a.append(&mut (2..1025).collect());
+
+    assert!(a.par_iter().find_map_any(half_if_positive).is_some());
+    assert_eq!(a.par_iter().find_map_first(half_if_positive), Some(1_i32));
+    assert_eq!(a.par_iter().find_map_last(half_if_positive), Some(512_i32));
+
+    fn half_if_positive(x: &i32) -> Option<i32> {
+        if *x > 0 {
+            Some(x / 2)
+        } else {
+            None
+        }
+    }
+
+    fn half_if_negative(x: &i32) -> Option<i32> {
+        if *x < 0 {
+            Some(x / 2)
+        } else {
+            None
+        }
+    }
+}
+
+#[test]
+fn check_find_not_present() {
+    let counter = AtomicUsize::new(0);
+    let value: Option<i32> = (0_i32..2048).into_par_iter().find_any(|&p| {
+        counter.fetch_add(1, Ordering::SeqCst);
+        p >= 2048
+    });
+    assert!(value.is_none());
+    assert!(counter.load(Ordering::SeqCst) == 2048); // should have visited every single one
+}
+
+#[test]
+fn check_find_is_present() {
+    let counter = AtomicUsize::new(0);
+    let value: Option<i32> = (0_i32..2048).into_par_iter().find_any(|&p| {
+        counter.fetch_add(1, Ordering::SeqCst);
+        (1024..1096).contains(&p)
+    });
+    let q = value.unwrap();
+    assert!((1024..1096).contains(&q));
+    assert!(counter.load(Ordering::SeqCst) < 2048); // should not have visited every single one
+}
+
+#[test]
+fn check_while_some() {
+    let value = (0_i32..2048).into_par_iter().map(Some).while_some().max();
+    assert_eq!(value, Some(2047));
+
+    let counter = AtomicUsize::new(0);
+    let value = (0_i32..2048)
+        .into_par_iter()
+        .map(|x| {
+            counter.fetch_add(1, Ordering::SeqCst);
+            if x < 1024 {
+                Some(x)
+            } else {
+                None
+            }
+        })
+        .while_some()
+        .max();
+    assert!(value < Some(1024));
+    assert!(counter.load(Ordering::SeqCst) < 2048); // should not have visited every single one
+}
+
+#[test]
+fn par_iter_collect_option() {
+    let a: Option<Vec<_>> = (0_i32..2048).map(Some).collect();
+    let b: Option<Vec<_>> = (0_i32..2048).into_par_iter().map(Some).collect();
+    assert_eq!(a, b);
+
+    let c: Option<Vec<_>> = (0_i32..2048)
+        .into_par_iter()
+        .map(|x| if x == 1234 { None } else { Some(x) })
+        .collect();
+    assert_eq!(c, None);
+}
+
+#[test]
+fn par_iter_collect_result() {
+    let a: Result<Vec<_>, ()> = (0_i32..2048).map(Ok).collect();
+    let b: Result<Vec<_>, ()> = (0_i32..2048).into_par_iter().map(Ok).collect();
+    assert_eq!(a, b);
+
+    let c: Result<Vec<_>, _> = (0_i32..2048)
+        .into_par_iter()
+        .map(|x| if x == 1234 { Err(x) } else { Ok(x) })
+        .collect();
+    assert_eq!(c, Err(1234));
+
+    let d: Result<Vec<_>, _> = (0_i32..2048)
+        .into_par_iter()
+        .map(|x| if x % 100 == 99 { Err(x) } else { Ok(x) })
+        .collect();
+    assert_eq!(d.map_err(|x| x % 100), Err(99));
+}
+
+#[test]
+fn par_iter_collect() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: Vec<i32> = a.par_iter().map(|&i| i + 1).collect();
+    let c: Vec<i32> = (0..1024).map(|i| i + 1).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn par_iter_collect_vecdeque() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: VecDeque<i32> = a.par_iter().cloned().collect();
+    let c: VecDeque<i32> = a.iter().cloned().collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn par_iter_collect_binaryheap() {
+    let a: Vec<i32> = (0..1024).collect();
+    let mut b: BinaryHeap<i32> = a.par_iter().cloned().collect();
+    assert_eq!(b.peek(), Some(&1023));
+    assert_eq!(b.len(), 1024);
+    for n in (0..1024).rev() {
+        assert_eq!(b.pop(), Some(n));
+        assert_eq!(b.len() as i32, n);
+    }
+}
+
+#[test]
+fn par_iter_collect_hashmap() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: HashMap<i32, String> = a.par_iter().map(|&i| (i, format!("{}", i))).collect();
+    assert_eq!(&b[&3], "3");
+    assert_eq!(b.len(), 1024);
+}
+
+#[test]
+fn par_iter_collect_hashset() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: HashSet<i32> = a.par_iter().cloned().collect();
+    assert_eq!(b.len(), 1024);
+}
+
+#[test]
+fn par_iter_collect_btreemap() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: BTreeMap<i32, String> = a.par_iter().map(|&i| (i, format!("{}", i))).collect();
+    assert_eq!(&b[&3], "3");
+    assert_eq!(b.len(), 1024);
+}
+
+#[test]
+fn par_iter_collect_btreeset() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: BTreeSet<i32> = a.par_iter().cloned().collect();
+    assert_eq!(b.len(), 1024);
+}
+
+#[test]
+fn par_iter_collect_linked_list() {
+    let a: Vec<i32> = (0..1024).collect();
+    let b: LinkedList<_> = a.par_iter().map(|&i| (i, format!("{}", i))).collect();
+    let c: LinkedList<_> = a.iter().map(|&i| (i, format!("{}", i))).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn par_iter_collect_linked_list_flat_map_filter() {
+    let b: LinkedList<i32> = (0_i32..1024)
+        .into_par_iter()
+        .flat_map(|i| (0..i))
+        .filter(|&i| i % 2 == 0)
+        .collect();
+    let c: LinkedList<i32> = (0_i32..1024)
+        .flat_map(|i| (0..i))
+        .filter(|&i| i % 2 == 0)
+        .collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn par_iter_collect_cows() {
+    use std::borrow::Cow;
+
+    let s = "Fearless Concurrency with Rust";
+
+    // Collects `i32` into a `Vec`
+    let a: Cow<'_, [i32]> = (0..1024).collect();
+    let b: Cow<'_, [i32]> = a.par_iter().cloned().collect();
+    assert_eq!(a, b);
+
+    // Collects `char` into a `String`
+    let a: Cow<'_, str> = s.chars().collect();
+    let b: Cow<'_, str> = s.par_chars().collect();
+    assert_eq!(a, b);
+
+    // Collects `str` into a `String`
+    let a: Cow<'_, str> = s.split_whitespace().collect();
+    let b: Cow<'_, str> = s.par_split_whitespace().collect();
+    assert_eq!(a, b);
+
+    // Collects `String` into a `String`
+    let a: Cow<'_, str> = s.split_whitespace().map(str::to_owned).collect();
+    let b: Cow<'_, str> = s.par_split_whitespace().map(str::to_owned).collect();
+    assert_eq!(a, b);
+}
+
+#[test]
+fn par_iter_unindexed_flat_map() {
+    let b: Vec<i64> = (0_i64..1024).into_par_iter().flat_map(Some).collect();
+    let c: Vec<i64> = (0_i64..1024).flat_map(Some).collect();
+    assert_eq!(b, c);
+}
+
+#[test]
+fn min_max() {
+    let rng = seeded_rng();
+    let a: Vec<i32> = rng.sample_iter(&Standard).take(1024).collect();
+    for i in 0..=a.len() {
+        let slice = &a[..i];
+        assert_eq!(slice.par_iter().min(), slice.iter().min());
+        assert_eq!(slice.par_iter().max(), slice.iter().max());
+    }
+}
+
+#[test]
+fn min_max_by() {
+    let rng = seeded_rng();
+    // Make sure there are duplicate keys, for testing sort stability
+    let r: Vec<i32> = rng.sample_iter(&Standard).take(512).collect();
+    let a: Vec<(i32, u16)> = r.iter().chain(&r).cloned().zip(0..).collect();
+    for i in 0..=a.len() {
+        let slice = &a[..i];
+        assert_eq!(
+            slice.par_iter().min_by(|x, y| x.0.cmp(&y.0)),
+            slice.iter().min_by(|x, y| x.0.cmp(&y.0))
+        );
+        assert_eq!(
+            slice.par_iter().max_by(|x, y| x.0.cmp(&y.0)),
+            slice.iter().max_by(|x, y| x.0.cmp(&y.0))
+        );
+    }
+}
+
+#[test]
+fn min_max_by_key() {
+    let rng = seeded_rng();
+    // Make sure there are duplicate keys, for testing sort stability
+    let r: Vec<i32> = rng.sample_iter(&Standard).take(512).collect();
+    let a: Vec<(i32, u16)> = r.iter().chain(&r).cloned().zip(0..).collect();
+    for i in 0..=a.len() {
+        let slice = &a[..i];
+        assert_eq!(
+            slice.par_iter().min_by_key(|x| x.0),
+            slice.iter().min_by_key(|x| x.0)
+        );
+        assert_eq!(
+            slice.par_iter().max_by_key(|x| x.0),
+            slice.iter().max_by_key(|x| x.0)
+        );
+    }
+}
+
+#[test]
+fn check_rev() {
+    let a: Vec<usize> = (0..1024).rev().collect();
+    let b: Vec<usize> = (0..1024).collect();
+
+    assert!(a.par_iter().rev().zip(b).all(|(&a, b)| a == b));
+}
+
+#[test]
+fn scope_mix() {
+    let counter_p = &AtomicUsize::new(0);
+    scope(|s| {
+        s.spawn(move |s| {
+            divide_and_conquer(s, counter_p, 1024);
+        });
+        s.spawn(move |_| {
+            let a: Vec<i32> = (0..1024).collect();
+            let r1 = a.par_iter().map(|&i| i + 1).reduce_with(|i, j| i + j);
+            let r2 = a.iter().map(|&i| i + 1).sum();
+            assert_eq!(r1.unwrap(), r2);
+        });
+    });
+}
+
+fn divide_and_conquer<'scope>(scope: &Scope<'scope>, counter: &'scope AtomicUsize, size: usize) {
+    if size > 1 {
+        scope.spawn(move |scope| divide_and_conquer(scope, counter, size / 2));
+        scope.spawn(move |scope| divide_and_conquer(scope, counter, size / 2));
+    } else {
+        // count the leaves
+        counter.fetch_add(1, Ordering::SeqCst);
+    }
+}
+
+#[test]
+fn check_split() {
+    use std::ops::Range;
+
+    let a = (0..1024).into_par_iter();
+
+    let b = split(0..1024, |Range { start, end }| {
+        let mid = (end - start) / 2;
+        if mid > start {
+            (start..mid, Some(mid..end))
+        } else {
+            (start..end, None)
+        }
+    })
+    .flat_map(|range| range);
+
+    assert_eq!(a.collect::<Vec<_>>(), b.collect::<Vec<_>>());
+}
+
+#[test]
+fn check_lengths() {
+    fn check(min: usize, max: usize) {
+        let range = 0..1024 * 1024;
+
+        // Check against normalized values.
+        let min_check = cmp::min(cmp::max(min, 1), range.len());
+        let max_check = cmp::max(max, min_check.saturating_add(min_check - 1));
+
+        assert!(
+            range
+                .into_par_iter()
+                .with_min_len(min)
+                .with_max_len(max)
+                .fold(|| 0, |count, _| count + 1)
+                .all(|c| c >= min_check && c <= max_check),
+            "check_lengths failed {:?} -> {:?} ",
+            (min, max),
+            (min_check, max_check)
+        );
+    }
+
+    let lengths = [0, 1, 10, 100, 1_000, 10_000, 100_000, 1_000_000, usize::MAX];
+    for &min in &lengths {
+        for &max in &lengths {
+            check(min, max);
+        }
+    }
+}
+
+#[test]
+fn check_map_with() {
+    let (sender, receiver) = mpsc::channel();
+    let a: HashSet<_> = (0..1024).collect();
+
+    a.par_iter()
+        .cloned()
+        .map_with(sender, |s, i| s.send(i).unwrap())
+        .count();
+
+    let b: HashSet<_> = receiver.iter().collect();
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_fold_with() {
+    let (sender, receiver) = mpsc::channel();
+    let a: HashSet<_> = (0..1024).collect();
+
+    a.par_iter()
+        .cloned()
+        .fold_with(sender, |s, i| {
+            s.send(i).unwrap();
+            s
+        })
+        .count();
+
+    let b: HashSet<_> = receiver.iter().collect();
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_for_each_with() {
+    let (sender, receiver) = mpsc::channel();
+    let a: HashSet<_> = (0..1024).collect();
+
+    a.par_iter()
+        .cloned()
+        .for_each_with(sender, |s, i| s.send(i).unwrap());
+
+    let b: HashSet<_> = receiver.iter().collect();
+    assert_eq!(a, b);
+}
+
+#[test]
+fn check_extend_items() {
+    fn check<C>()
+    where
+        C: Default
+            + Eq
+            + Debug
+            + Extend<i32>
+            + for<'a> Extend<&'a i32>
+            + ParallelExtend<i32>
+            + for<'a> ParallelExtend<&'a i32>,
+    {
+        let mut serial = C::default();
+        let mut parallel = C::default();
+
+        // extend with references
+        let v: Vec<_> = (0..128).collect();
+        serial.extend(&v);
+        parallel.par_extend(&v);
+        assert_eq!(serial, parallel);
+
+        // extend with values
+        serial.extend(-128..0);
+        parallel.par_extend(-128..0);
+        assert_eq!(serial, parallel);
+    }
+
+    check::<BTreeSet<_>>();
+    check::<HashSet<_>>();
+    check::<LinkedList<_>>();
+    check::<Vec<_>>();
+    check::<VecDeque<_>>();
+}
+
+#[test]
+fn check_extend_heap() {
+    let mut serial: BinaryHeap<_> = Default::default();
+    let mut parallel: BinaryHeap<_> = Default::default();
+
+    // extend with references
+    let v: Vec<_> = (0..128).collect();
+    serial.extend(&v);
+    parallel.par_extend(&v);
+    assert_eq!(
+        serial.clone().into_sorted_vec(),
+        parallel.clone().into_sorted_vec()
+    );
+
+    // extend with values
+    serial.extend(-128..0);
+    parallel.par_extend(-128..0);
+    assert_eq!(serial.into_sorted_vec(), parallel.into_sorted_vec());
+}
+
+#[test]
+fn check_extend_pairs() {
+    fn check<C>()
+    where
+        C: Default
+            + Eq
+            + Debug
+            + Extend<(usize, i32)>
+            + for<'a> Extend<(&'a usize, &'a i32)>
+            + ParallelExtend<(usize, i32)>
+            + for<'a> ParallelExtend<(&'a usize, &'a i32)>,
+    {
+        let mut serial = C::default();
+        let mut parallel = C::default();
+
+        // extend with references
+        let m: HashMap<_, _> = (0..128).enumerate().collect();
+        serial.extend(&m);
+        parallel.par_extend(&m);
+        assert_eq!(serial, parallel);
+
+        // extend with values
+        let v: Vec<(_, _)> = (-128..0).enumerate().collect();
+        serial.extend(v.clone());
+        parallel.par_extend(v);
+        assert_eq!(serial, parallel);
+    }
+
+    check::<BTreeMap<usize, i32>>();
+    check::<HashMap<usize, i32>>();
+}
+
+#[test]
+fn check_unzip_into_vecs() {
+    let mut a = vec![];
+    let mut b = vec![];
+    (0..1024)
+        .into_par_iter()
+        .map(|i| i * i)
+        .enumerate()
+        .unzip_into_vecs(&mut a, &mut b);
+
+    let (c, d): (Vec<_>, Vec<_>) = (0..1024).map(|i| i * i).enumerate().unzip();
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+}
+
+#[test]
+fn check_unzip() {
+    // indexed, unindexed
+    let (a, b): (Vec<_>, HashSet<_>) = (0..1024).into_par_iter().map(|i| i * i).enumerate().unzip();
+    let (c, d): (Vec<_>, HashSet<_>) = (0..1024).map(|i| i * i).enumerate().unzip();
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+
+    // unindexed, indexed
+    let (a, b): (HashSet<_>, Vec<_>) = (0..1024).into_par_iter().map(|i| i * i).enumerate().unzip();
+    let (c, d): (HashSet<_>, Vec<_>) = (0..1024).map(|i| i * i).enumerate().unzip();
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+
+    // indexed, indexed
+    let (a, b): (Vec<_>, Vec<_>) = (0..1024).into_par_iter().map(|i| i * i).enumerate().unzip();
+    let (c, d): (Vec<_>, Vec<_>) = (0..1024).map(|i| i * i).enumerate().unzip();
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+
+    // unindexed producer
+    let (a, b): (Vec<_>, Vec<_>) = (0..1024)
+        .into_par_iter()
+        .filter_map(|i| Some((i, i * i)))
+        .unzip();
+    let (c, d): (Vec<_>, Vec<_>) = (0..1024).map(|i| (i, i * i)).unzip();
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+}
+
+#[test]
+fn check_partition() {
+    let (a, b): (Vec<_>, Vec<_>) = (0..1024).into_par_iter().partition(|&i| i % 3 == 0);
+    let (c, d): (Vec<_>, Vec<_>) = (0..1024).partition(|&i| i % 3 == 0);
+    assert_eq!(a, c);
+    assert_eq!(b, d);
+}
+
+#[test]
+fn check_partition_map() {
+    let input = "a b c 1 2 3 x y z";
+    let (a, b): (Vec<_>, String) =
+        input
+            .par_split_whitespace()
+            .partition_map(|s| match s.parse::<i32>() {
+                Ok(n) => Either::Left(n),
+                Err(_) => Either::Right(s),
+            });
+    assert_eq!(a, vec![1, 2, 3]);
+    assert_eq!(b, "abcxyz");
+}
+
+#[test]
+fn check_either() {
+    type I = crate::vec::IntoIter<i32>;
+    type E = Either<I, I>;
+
+    let v: Vec<i32> = (0..1024).collect();
+
+    // try iterating the left side
+    let left: E = Either::Left(v.clone().into_par_iter());
+    assert!(left.eq(v.clone()));
+
+    // try iterating the right side
+    let right: E = Either::Right(v.clone().into_par_iter());
+    assert!(right.eq(v.clone()));
+
+    // try an indexed iterator
+    let left: E = Either::Left(v.clone().into_par_iter());
+    assert!(left.enumerate().eq(v.into_par_iter().enumerate()));
+}
+
+#[test]
+fn check_either_extend() {
+    type E = Either<Vec<i32>, HashSet<i32>>;
+
+    let v: Vec<i32> = (0..1024).collect();
+
+    // try extending the left side
+    let mut left: E = Either::Left(vec![]);
+    left.par_extend(v.clone());
+    assert_eq!(left.as_ref(), Either::Left(&v));
+
+    // try extending the right side
+    let mut right: E = Either::Right(HashSet::default());
+    right.par_extend(v.clone());
+    assert_eq!(right, Either::Right(v.iter().cloned().collect()));
+}
+
+#[test]
+fn check_interleave_eq() {
+    let xs: Vec<usize> = (0..10).collect();
+    let ys: Vec<usize> = (10..20).collect();
+
+    let mut actual = vec![];
+    xs.par_iter()
+        .interleave(&ys)
+        .map(|&i| i)
+        .collect_into_vec(&mut actual);
+
+    let expected: Vec<usize> = (0..10)
+        .zip(10..20)
+        .flat_map(|(i, j)| vec![i, j].into_iter())
+        .collect();
+    assert_eq!(expected, actual);
+}
+
+#[test]
+fn check_interleave_uneven() {
+    let cases: Vec<(Vec<usize>, Vec<usize>, Vec<usize>)> = vec![
+        (
+            (0..9).collect(),
+            vec![10],
+            vec![0, 10, 1, 2, 3, 4, 5, 6, 7, 8],
+        ),
+        (
+            vec![10],
+            (0..9).collect(),
+            vec![10, 0, 1, 2, 3, 4, 5, 6, 7, 8],
+        ),
+        (
+            (0..5).collect(),
+            (5..10).collect(),
+            (0..5)
+                .zip(5..10)
+                .flat_map(|(i, j)| vec![i, j].into_iter())
+                .collect(),
+        ),
+        (vec![], (0..9).collect(), (0..9).collect()),
+        ((0..9).collect(), vec![], (0..9).collect()),
+        (
+            (0..50).collect(),
+            (50..100).collect(),
+            (0..50)
+                .zip(50..100)
+                .flat_map(|(i, j)| vec![i, j].into_iter())
+                .collect(),
+        ),
+    ];
+
+    for (i, (xs, ys, expected)) in cases.into_iter().enumerate() {
+        let mut res = vec![];
+        xs.par_iter()
+            .interleave(&ys)
+            .map(|&i| i)
+            .collect_into_vec(&mut res);
+        assert_eq!(expected, res, "Case {} failed", i);
+
+        res.truncate(0);
+        xs.par_iter()
+            .interleave(&ys)
+            .rev()
+            .map(|&i| i)
+            .collect_into_vec(&mut res);
+        assert_eq!(
+            expected.into_iter().rev().collect::<Vec<usize>>(),
+            res,
+            "Case {} reversed failed",
+            i
+        );
+    }
+}
+
+#[test]
+fn check_interleave_shortest() {
+    let cases: Vec<(Vec<usize>, Vec<usize>, Vec<usize>)> = vec![
+        ((0..9).collect(), vec![10], vec![0, 10, 1]),
+        (vec![10], (0..9).collect(), vec![10, 0]),
+        (
+            (0..5).collect(),
+            (5..10).collect(),
+            (0..5)
+                .zip(5..10)
+                .flat_map(|(i, j)| vec![i, j].into_iter())
+                .collect(),
+        ),
+        (vec![], (0..9).collect(), vec![]),
+        ((0..9).collect(), vec![], vec![0]),
+        (
+            (0..50).collect(),
+            (50..100).collect(),
+            (0..50)
+                .zip(50..100)
+                .flat_map(|(i, j)| vec![i, j].into_iter())
+                .collect(),
+        ),
+    ];
+
+    for (i, (xs, ys, expected)) in cases.into_iter().enumerate() {
+        let mut res = vec![];
+        xs.par_iter()
+            .interleave_shortest(&ys)
+            .map(|&i| i)
+            .collect_into_vec(&mut res);
+        assert_eq!(expected, res, "Case {} failed", i);
+
+        res.truncate(0);
+        xs.par_iter()
+            .interleave_shortest(&ys)
+            .rev()
+            .map(|&i| i)
+            .collect_into_vec(&mut res);
+        assert_eq!(
+            expected.into_iter().rev().collect::<Vec<usize>>(),
+            res,
+            "Case {} reversed failed",
+            i
+        );
+    }
+}
+
+#[test]
+#[should_panic(expected = "chunk_size must not be zero")]
+fn check_chunks_zero_size() {
+    let _: Vec<Vec<i32>> = vec![1, 2, 3].into_par_iter().chunks(0).collect();
+}
+
+#[test]
+fn check_chunks_even_size() {
+    assert_eq!(
+        vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]],
+        (1..10).into_par_iter().chunks(3).collect::<Vec<Vec<i32>>>()
+    );
+}
+
+#[test]
+fn check_chunks_empty() {
+    let v: Vec<i32> = vec![];
+    let expected: Vec<Vec<i32>> = vec![];
+    assert_eq!(
+        expected,
+        v.into_par_iter().chunks(2).collect::<Vec<Vec<i32>>>()
+    );
+}
+
+#[test]
+fn check_chunks_len() {
+    assert_eq!(4, (0..8).into_par_iter().chunks(2).len());
+    assert_eq!(3, (0..9).into_par_iter().chunks(3).len());
+    assert_eq!(3, (0..8).into_par_iter().chunks(3).len());
+    assert_eq!(1, [1].par_iter().chunks(3).len());
+    assert_eq!(0, (0..0).into_par_iter().chunks(3).len());
+}
+
+#[test]
+fn check_chunks_uneven() {
+    let cases: Vec<(Vec<u32>, usize, Vec<Vec<u32>>)> = vec![
+        ((0..5).collect(), 3, vec![vec![0, 1, 2], vec![3, 4]]),
+        (vec![1], 5, vec![vec![1]]),
+        ((0..4).collect(), 3, vec![vec![0, 1, 2], vec![3]]),
+    ];
+
+    for (i, (v, n, expected)) in cases.into_iter().enumerate() {
+        let mut res: Vec<Vec<u32>> = vec![];
+        v.par_iter()
+            .chunks(n)
+            .map(|v| v.into_iter().cloned().collect())
+            .collect_into_vec(&mut res);
+        assert_eq!(expected, res, "Case {} failed", i);
+
+        res.truncate(0);
+        v.into_par_iter().chunks(n).rev().collect_into_vec(&mut res);
+        assert_eq!(
+            expected.into_iter().rev().collect::<Vec<Vec<u32>>>(),
+            res,
+            "Case {} reversed failed",
+            i
+        );
+    }
+}
+
+#[test]
+#[ignore] // it's quick enough on optimized 32-bit platforms, but otherwise... ... ...
+#[should_panic(expected = "overflow")]
+#[cfg(debug_assertions)]
+fn check_repeat_unbounded() {
+    // use just one thread, so we don't get infinite adaptive splitting
+    // (forever stealing and re-splitting jobs that will panic on overflow)
+    let pool = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+    pool.install(|| {
+        println!("counted {} repeats", repeat(()).count());
+    });
+}
+
+#[test]
+fn check_repeat_find_any() {
+    let even = repeat(4).find_any(|&x| x % 2 == 0);
+    assert_eq!(even, Some(4));
+}
+
+#[test]
+fn check_repeat_take() {
+    let v: Vec<_> = repeat(4).take(4).collect();
+    assert_eq!(v, [4, 4, 4, 4]);
+}
+
+#[test]
+fn check_repeat_zip() {
+    let v = vec![4, 4, 4, 4];
+    let mut fours: Vec<_> = repeat(4).zip(v).collect();
+    assert_eq!(fours.len(), 4);
+    while let Some(item) = fours.pop() {
+        assert_eq!(item, (4, 4));
+    }
+}
+
+#[test]
+fn check_repeatn_zip_left() {
+    let v = vec![4, 4, 4, 4];
+    let mut fours: Vec<_> = repeatn(4, usize::MAX).zip(v).collect();
+    assert_eq!(fours.len(), 4);
+    while let Some(item) = fours.pop() {
+        assert_eq!(item, (4, 4));
+    }
+}
+
+#[test]
+fn check_repeatn_zip_right() {
+    let v = vec![4, 4, 4, 4];
+    let mut fours: Vec<_> = v.into_par_iter().zip(repeatn(4, usize::MAX)).collect();
+    assert_eq!(fours.len(), 4);
+    while let Some(item) = fours.pop() {
+        assert_eq!(item, (4, 4));
+    }
+}
+
+#[test]
+fn check_empty() {
+    // drive_unindexed
+    let mut v: Vec<i32> = empty().filter(|_| unreachable!()).collect();
+    assert!(v.is_empty());
+
+    // drive (indexed)
+    empty().collect_into_vec(&mut v);
+    assert!(v.is_empty());
+
+    // with_producer
+    let v: Vec<(i32, i32)> = empty().zip(1..10).collect();
+    assert!(v.is_empty());
+}
+
+#[test]
+fn check_once() {
+    // drive_unindexed
+    let mut v: Vec<i32> = once(42).filter(|_| true).collect();
+    assert_eq!(v, &[42]);
+
+    // drive (indexed)
+    once(42).collect_into_vec(&mut v);
+    assert_eq!(v, &[42]);
+
+    // with_producer
+    let v: Vec<(i32, i32)> = once(42).zip(1..10).collect();
+    assert_eq!(v, &[(42, 1)]);
+}
+
+#[test]
+fn check_update() {
+    let mut v: Vec<Vec<_>> = vec![vec![1], vec![3, 2, 1]];
+    v.par_iter_mut().update(|v| v.push(0)).for_each(|_| ());
+
+    assert_eq!(v, vec![vec![1, 0], vec![3, 2, 1, 0]]);
+}