Vendor dependencies for 0.3.0 release

vendor/itertools/tests/adaptors_no_collect.rs

@@ -0,0 +1,51 @@
+use itertools::Itertools;
+
+struct PanickingCounter {
+    curr: usize,
+    max: usize,
+}
+
+impl Iterator for PanickingCounter {
+    type Item = ();
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.curr += 1;
+
+        assert_ne!(
+            self.curr, self.max,
+            "Input iterator reached maximum of {} suggesting collection by adaptor",
+            self.max
+        );
+
+        Some(())
+    }
+}
+
+fn no_collect_test<A, T>(to_adaptor: T)
+where
+    A: Iterator,
+    T: Fn(PanickingCounter) -> A,
+{
+    let counter = PanickingCounter {
+        curr: 0,
+        max: 10_000,
+    };
+    let adaptor = to_adaptor(counter);
+
+    for _ in adaptor.take(5) {}
+}
+
+#[test]
+fn permutations_no_collect() {
+    no_collect_test(|iter| iter.permutations(5))
+}
+
+#[test]
+fn combinations_no_collect() {
+    no_collect_test(|iter| iter.combinations(5))
+}
+
+#[test]
+fn combinations_with_replacement_no_collect() {
+    no_collect_test(|iter| iter.combinations_with_replacement(5))
+}

vendor/itertools/tests/flatten_ok.rs

@@ -0,0 +1,76 @@
+use itertools::{assert_equal, Itertools};
+use std::{ops::Range, vec::IntoIter};
+
+fn mix_data() -> IntoIter<Result<Range<i32>, bool>> {
+    vec![Ok(0..2), Err(false), Ok(2..4), Err(true), Ok(4..6)].into_iter()
+}
+
+fn ok_data() -> IntoIter<Result<Range<i32>, bool>> {
+    vec![Ok(0..2), Ok(2..4), Ok(4..6)].into_iter()
+}
+
+#[test]
+fn flatten_ok_mixed_expected_forward() {
+    assert_equal(
+        mix_data().flatten_ok(),
+        vec![
+            Ok(0),
+            Ok(1),
+            Err(false),
+            Ok(2),
+            Ok(3),
+            Err(true),
+            Ok(4),
+            Ok(5),
+        ],
+    );
+}
+
+#[test]
+fn flatten_ok_mixed_expected_reverse() {
+    assert_equal(
+        mix_data().flatten_ok().rev(),
+        vec![
+            Ok(5),
+            Ok(4),
+            Err(true),
+            Ok(3),
+            Ok(2),
+            Err(false),
+            Ok(1),
+            Ok(0),
+        ],
+    );
+}
+
+#[test]
+fn flatten_ok_collect_mixed_forward() {
+    assert_eq!(
+        mix_data().flatten_ok().collect::<Result<Vec<_>, _>>(),
+        Err(false)
+    );
+}
+
+#[test]
+fn flatten_ok_collect_mixed_reverse() {
+    assert_eq!(
+        mix_data().flatten_ok().rev().collect::<Result<Vec<_>, _>>(),
+        Err(true)
+    );
+}
+
+#[test]
+fn flatten_ok_collect_ok_forward() {
+    assert_eq!(
+        ok_data().flatten_ok().collect::<Result<Vec<_>, _>>(),
+        Ok((0..6).collect())
+    );
+}
+
+#[test]
+fn flatten_ok_collect_ok_reverse() {
+    assert_eq!(
+        ok_data().flatten_ok().rev().collect::<Result<Vec<_>, _>>(),
+        Ok((0..6).rev().collect())
+    );
+}

vendor/itertools/tests/laziness.rs

@@ -0,0 +1,283 @@
+#![allow(unstable_name_collisions)]
+
+use itertools::Itertools;
+
+#[derive(Debug, Clone)]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+struct Panicking;
+
+impl Iterator for Panicking {
+    type Item = u8;
+
+    fn next(&mut self) -> Option<u8> {
+        panic!("iterator adaptor is not lazy")
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (0, Some(0))
+    }
+}
+
+impl ExactSizeIterator for Panicking {}
+
+/// ## Usage example
+/// ```compile_fail
+/// must_use_tests! {
+///     name {
+///         Panicking.name(); // Add `let _ =` only if required (encountered error).
+///     }
+///     // ...
+/// }
+/// ```
+///
+/// **TODO:** test missing `must_use` attributes better, maybe with a new lint.
+macro_rules! must_use_tests {
+    ($($(#[$attr:meta])* $name:ident $body:block)*) => {
+        $(
+            /// `#[deny(unused_must_use)]` should force us to ignore the resulting iterators
+            /// by adding `let _ = ...;` on every iterator.
+            /// If it does not, then a `must_use` attribute is missing on the associated struct.
+            ///
+            /// However, it's only helpful if we don't add `let _ =` before seeing if there is an error or not.
+            /// And it does not protect us against removed `must_use` attributes.
+            /// There is no simple way to test this yet.
+            #[deny(unused_must_use)]
+            #[test]
+            $(#[$attr])*
+            fn $name() $body
+        )*
+    };
+}
+
+must_use_tests! {
+    // Itertools trait:
+    interleave {
+        let _ = Panicking.interleave(Panicking);
+    }
+    interleave_shortest {
+        let _ = Panicking.interleave_shortest(Panicking);
+    }
+    intersperse {
+        let _ = Panicking.intersperse(0);
+    }
+    intersperse_with {
+        let _ = Panicking.intersperse_with(|| 0);
+    }
+    get {
+        let _ = Panicking.get(1..4);
+        let _ = Panicking.get(1..=4);
+        let _ = Panicking.get(1..);
+        let _ = Panicking.get(..4);
+        let _ = Panicking.get(..=4);
+        let _ = Panicking.get(..);
+    }
+    zip_longest {
+        let _ = Panicking.zip_longest(Panicking);
+    }
+    zip_eq {
+        let _ = Panicking.zip_eq(Panicking);
+    }
+    batching {
+        let _ = Panicking.batching(Iterator::next);
+    }
+    chunk_by {
+        // ChunkBy
+        let _ = Panicking.chunk_by(|x| *x);
+        // Groups
+        let _ = Panicking.chunk_by(|x| *x).into_iter();
+    }
+    chunks {
+        // IntoChunks
+        let _ = Panicking.chunks(1);
+        let _ = Panicking.chunks(2);
+        // Chunks
+        let _ = Panicking.chunks(1).into_iter();
+        let _ = Panicking.chunks(2).into_iter();
+    }
+    tuple_windows {
+        let _ = Panicking.tuple_windows::<(_,)>();
+        let _ = Panicking.tuple_windows::<(_, _)>();
+        let _ = Panicking.tuple_windows::<(_, _, _)>();
+    }
+    circular_tuple_windows {
+        let _ = Panicking.circular_tuple_windows::<(_,)>();
+        let _ = Panicking.circular_tuple_windows::<(_, _)>();
+        let _ = Panicking.circular_tuple_windows::<(_, _, _)>();
+    }
+    tuples {
+        let _ = Panicking.tuples::<(_,)>();
+        let _ = Panicking.tuples::<(_, _)>();
+        let _ = Panicking.tuples::<(_, _, _)>();
+    }
+    tee {
+        let _ = Panicking.tee();
+    }
+    map_into {
+        let _ = Panicking.map_into::<u16>();
+    }
+    map_ok {
+        let _ = Panicking.map(Ok::<u8, ()>).map_ok(|x| x + 1);
+    }
+    filter_ok {
+        let _ = Panicking.map(Ok::<u8, ()>).filter_ok(|x| x % 2 == 0);
+    }
+    filter_map_ok {
+        let _ = Panicking.map(Ok::<u8, ()>).filter_map_ok(|x| {
+            if x % 2 == 0 {
+                Some(x + 1)
+            } else {
+                None
+            }
+        });
+    }
+    flatten_ok {
+        let _ = Panicking.map(|x| Ok::<_, ()>([x])).flatten_ok();
+    }
+    merge {
+        let _ = Panicking.merge(Panicking);
+    }
+    merge_by {
+        let _ = Panicking.merge_by(Panicking, |_, _| true);
+    }
+    merge_join_by {
+        let _ = Panicking.merge_join_by(Panicking, |_, _| true);
+        let _ = Panicking.merge_join_by(Panicking, Ord::cmp);
+    }
+    #[should_panic]
+    kmerge {
+        let _ = Panicking.map(|_| Panicking).kmerge();
+    }
+    #[should_panic]
+    kmerge_by {
+        let _ = Panicking.map(|_| Panicking).kmerge_by(|_, _| true);
+    }
+    cartesian_product {
+        let _ = Panicking.cartesian_product(Panicking);
+    }
+    multi_cartesian_product {
+        let _ = vec![Panicking, Panicking, Panicking].into_iter().multi_cartesian_product();
+    }
+    coalesce {
+        let _ = Panicking.coalesce(|x, y| if x == y { Ok(x) } else { Err((x, y)) });
+    }
+    dedup {
+        let _ = Panicking.dedup();
+    }
+    dedup_by {
+        let _ = Panicking.dedup_by(|_, _| true);
+    }
+    dedup_with_count {
+        let _ = Panicking.dedup_with_count();
+    }
+    dedup_by_with_count {
+        let _ = Panicking.dedup_by_with_count(|_, _| true);
+    }
+    duplicates {
+        let _ = Panicking.duplicates();
+    }
+    duplicates_by {
+        let _ = Panicking.duplicates_by(|x| *x);
+    }
+    unique {
+        let _ = Panicking.unique();
+    }
+    unique_by {
+        let _ = Panicking.unique_by(|x| *x);
+    }
+    peeking_take_while {
+        let _ = Panicking.peekable().peeking_take_while(|x| x % 2 == 0);
+    }
+    take_while_ref {
+        let _ = Panicking.take_while_ref(|x| x % 2 == 0);
+    }
+    take_while_inclusive {
+        let _ = Panicking.take_while_inclusive(|x| x % 2 == 0);
+    }
+    while_some {
+        let _ = Panicking.map(Some).while_some();
+    }
+    tuple_combinations1 {
+        let _ = Panicking.tuple_combinations::<(_,)>();
+    }
+    #[should_panic]
+    tuple_combinations2 {
+        let _ = Panicking.tuple_combinations::<(_, _)>();
+    }
+    #[should_panic]
+    tuple_combinations3 {
+        let _ = Panicking.tuple_combinations::<(_, _, _)>();
+    }
+    combinations {
+        let _ = Panicking.combinations(0);
+        let _ = Panicking.combinations(1);
+        let _ = Panicking.combinations(2);
+    }
+    combinations_with_replacement {
+        let _ = Panicking.combinations_with_replacement(0);
+        let _ = Panicking.combinations_with_replacement(1);
+        let _ = Panicking.combinations_with_replacement(2);
+    }
+    permutations {
+        let _ = Panicking.permutations(0);
+        let _ = Panicking.permutations(1);
+        let _ = Panicking.permutations(2);
+    }
+    powerset {
+        let _ = Panicking.powerset();
+    }
+    pad_using {
+        let _ = Panicking.pad_using(25, |_| 10);
+    }
+    with_position {
+        let _ = Panicking.with_position();
+    }
+    positions {
+        let _ = Panicking.positions(|v| v % 2 == 0);
+    }
+    update {
+        let _ = Panicking.update(|n| *n += 1);
+    }
+    multipeek {
+        let _ = Panicking.multipeek();
+    }
+    // Not iterator themselves but still lazy.
+    into_grouping_map {
+        let _ = Panicking.map(|x| (x, x + 1)).into_grouping_map();
+    }
+    into_grouping_map_by {
+        let _ = Panicking.into_grouping_map_by(|x| *x);
+    }
+    // Macros:
+    iproduct {
+        let _ = itertools::iproduct!(Panicking);
+        let _ = itertools::iproduct!(Panicking, Panicking);
+        let _ = itertools::iproduct!(Panicking, Panicking, Panicking);
+    }
+    izip {
+        let _ = itertools::izip!(Panicking);
+        let _ = itertools::izip!(Panicking, Panicking);
+        let _ = itertools::izip!(Panicking, Panicking, Panicking);
+    }
+    chain {
+        let _ = itertools::chain!(Panicking);
+        let _ = itertools::chain!(Panicking, Panicking);
+        let _ = itertools::chain!(Panicking, Panicking, Panicking);
+    }
+    // Free functions:
+    multizip {
+        let _ = itertools::multizip((Panicking, Panicking));
+    }
+    put_back {
+        let _ = itertools::put_back(Panicking);
+        let _ = itertools::put_back(Panicking).with_value(15);
+    }
+    peek_nth {
+        let _ = itertools::peek_nth(Panicking);
+    }
+    put_back_n {
+        let _ = itertools::put_back_n(Panicking);
+    }
+    rciter {
+        let _ = itertools::rciter(Panicking);
+    }
+}

vendor/itertools/tests/macros_hygiene.rs

@@ -0,0 +1,27 @@
+mod alloc {}
+mod core {}
+mod either {}
+mod std {}
+
+#[test]
+fn iproduct_hygiene() {
+    let _ = itertools::iproduct!();
+    let _ = itertools::iproduct!(0..6);
+    let _ = itertools::iproduct!(0..6, 0..9);
+    let _ = itertools::iproduct!(0..6, 0..9, 0..12);
+}
+
+#[test]
+fn izip_hygiene() {
+    let _ = itertools::izip!(0..6);
+    let _ = itertools::izip!(0..6, 0..9);
+    let _ = itertools::izip!(0..6, 0..9, 0..12);
+}
+
+#[test]
+fn chain_hygiene() {
+    let _: ::std::iter::Empty<i32> = itertools::chain!();
+    let _ = itertools::chain!(0..6);
+    let _ = itertools::chain!(0..6, 0..9);
+    let _ = itertools::chain!(0..6, 0..9, 0..12);
+}

vendor/itertools/tests/merge_join.rs

@@ -0,0 +1,101 @@
+use itertools::free::merge_join_by;
+use itertools::EitherOrBoth;
+
+#[test]
+fn empty() {
+    let left: Vec<u32> = vec![];
+    let right: Vec<u32> = vec![];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn left_only() {
+    let left: Vec<u32> = vec![1, 2, 3];
+    let right: Vec<u32> = vec![];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Left(1),
+        EitherOrBoth::Left(2),
+        EitherOrBoth::Left(3),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn right_only() {
+    let left: Vec<u32> = vec![];
+    let right: Vec<u32> = vec![1, 2, 3];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Right(1),
+        EitherOrBoth::Right(2),
+        EitherOrBoth::Right(3),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn first_left_then_right() {
+    let left: Vec<u32> = vec![1, 2, 3];
+    let right: Vec<u32> = vec![4, 5, 6];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Left(1),
+        EitherOrBoth::Left(2),
+        EitherOrBoth::Left(3),
+        EitherOrBoth::Right(4),
+        EitherOrBoth::Right(5),
+        EitherOrBoth::Right(6),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn first_right_then_left() {
+    let left: Vec<u32> = vec![4, 5, 6];
+    let right: Vec<u32> = vec![1, 2, 3];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Right(1),
+        EitherOrBoth::Right(2),
+        EitherOrBoth::Right(3),
+        EitherOrBoth::Left(4),
+        EitherOrBoth::Left(5),
+        EitherOrBoth::Left(6),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn interspersed_left_and_right() {
+    let left: Vec<u32> = vec![1, 3, 5];
+    let right: Vec<u32> = vec![2, 4, 6];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Left(1),
+        EitherOrBoth::Right(2),
+        EitherOrBoth::Left(3),
+        EitherOrBoth::Right(4),
+        EitherOrBoth::Left(5),
+        EitherOrBoth::Right(6),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn overlapping_left_and_right() {
+    let left: Vec<u32> = vec![1, 3, 4, 6];
+    let right: Vec<u32> = vec![2, 3, 4, 5];
+    let expected_result: Vec<EitherOrBoth<u32>> = vec![
+        EitherOrBoth::Left(1),
+        EitherOrBoth::Right(2),
+        EitherOrBoth::Both(3, 3),
+        EitherOrBoth::Both(4, 4),
+        EitherOrBoth::Right(5),
+        EitherOrBoth::Left(6),
+    ];
+    let actual_result = merge_join_by(left, right, |l, r| l.cmp(r)).collect::<Vec<_>>();
+    assert_eq!(expected_result, actual_result);
+}

vendor/itertools/tests/peeking_take_while.rs

@@ -0,0 +1,69 @@
+use itertools::Itertools;
+use itertools::{put_back, put_back_n};
+
+#[test]
+fn peeking_take_while_peekable() {
+    let mut r = (0..10).peekable();
+    r.peeking_take_while(|x| *x <= 3).count();
+    assert_eq!(r.next(), Some(4));
+}
+
+#[test]
+fn peeking_take_while_put_back() {
+    let mut r = put_back(0..10);
+    r.peeking_take_while(|x| *x <= 3).count();
+    assert_eq!(r.next(), Some(4));
+    r.peeking_take_while(|_| true).count();
+    assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_put_back_n() {
+    let mut r = put_back_n(6..10);
+    for elt in (0..6).rev() {
+        r.put_back(elt);
+    }
+    r.peeking_take_while(|x| *x <= 3).count();
+    assert_eq!(r.next(), Some(4));
+    r.peeking_take_while(|_| true).count();
+    assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_slice_iter() {
+    let v = [1, 2, 3, 4, 5, 6];
+    let mut r = v.iter();
+    r.peeking_take_while(|x| **x <= 3).count();
+    assert_eq!(r.next(), Some(&4));
+    r.peeking_take_while(|_| true).count();
+    assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_slice_iter_rev() {
+    let v = [1, 2, 3, 4, 5, 6];
+    let mut r = v.iter().rev();
+    r.peeking_take_while(|x| **x >= 3).count();
+    assert_eq!(r.next(), Some(&2));
+    r.peeking_take_while(|_| true).count();
+    assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_nested() {
+    let mut xs = (0..10).peekable();
+    let ys: Vec<_> = xs
+        .peeking_take_while(|x| *x < 6)
+        .peeking_take_while(|x| *x != 3)
+        .collect();
+    assert_eq!(ys, vec![0, 1, 2]);
+    assert_eq!(xs.next(), Some(3));
+
+    let mut xs = (4..10).peekable();
+    let ys: Vec<_> = xs
+        .peeking_take_while(|x| *x != 3)
+        .peeking_take_while(|x| *x < 6)
+        .collect();
+    assert_eq!(ys, vec![4, 5]);
+    assert_eq!(xs.next(), Some(6));
+}

vendor/itertools/tests/specializations.rs

@@ -0,0 +1,603 @@
+//! Test specializations of methods with default impls match the behavior of the
+//! default impls.
+//!
+//! **NOTE:** Due to performance limitations, these tests are not run with miri!
+//! They cannot be relied upon to discover soundness issues.
+
+#![cfg(not(miri))]
+#![allow(unstable_name_collisions)]
+
+use itertools::Itertools;
+use quickcheck::Arbitrary;
+use quickcheck::{quickcheck, TestResult};
+use rand::Rng;
+use std::fmt::Debug;
+
+struct Unspecialized<I>(I);
+
+impl<I> Iterator for Unspecialized<I>
+where
+    I: Iterator,
+{
+    type Item = I::Item;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next()
+    }
+}
+
+impl<I> DoubleEndedIterator for Unspecialized<I>
+where
+    I: DoubleEndedIterator,
+{
+    #[inline(always)]
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.0.next_back()
+    }
+}
+
+fn test_specializations<I>(it: &I)
+where
+    I::Item: Eq + Debug + Clone,
+    I: Iterator + Clone,
+{
+    macro_rules! check_specialized {
+        ($src:expr, |$it:pat| $closure:expr) => {
+            // Many iterators special-case the first elements, so we test specializations for iterators that have already been advanced.
+            let mut src = $src.clone();
+            for _ in 0..5 {
+                let $it = src.clone();
+                let v1 = $closure;
+                let $it = Unspecialized(src.clone());
+                let v2 = $closure;
+                assert_eq!(v1, v2);
+                src.next();
+            }
+        }
+    }
+    check_specialized!(it, |i| i.count());
+    check_specialized!(it, |i| i.last());
+    check_specialized!(it, |i| i.collect::<Vec<_>>());
+    check_specialized!(it, |i| {
+        let mut parameters_from_fold = vec![];
+        let fold_result = i.fold(vec![], |mut acc, v: I::Item| {
+            parameters_from_fold.push((acc.clone(), v.clone()));
+            acc.push(v);
+            acc
+        });
+        (parameters_from_fold, fold_result)
+    });
+    check_specialized!(it, |mut i| {
+        let mut parameters_from_all = vec![];
+        let first = i.next();
+        let all_result = i.all(|x| {
+            parameters_from_all.push(x.clone());
+            Some(x) == first
+        });
+        (parameters_from_all, all_result)
+    });
+    let size = it.clone().count();
+    for n in 0..size + 2 {
+        check_specialized!(it, |mut i| i.nth(n));
+    }
+    // size_hint is a bit harder to check
+    let mut it_sh = it.clone();
+    for n in 0..size + 2 {
+        let len = it_sh.clone().count();
+        let (min, max) = it_sh.size_hint();
+        assert_eq!(size - n.min(size), len);
+        assert!(min <= len);
+        if let Some(max) = max {
+            assert!(len <= max);
+        }
+        it_sh.next();
+    }
+}
+
+fn test_double_ended_specializations<I>(it: &I)
+where
+    I::Item: Eq + Debug + Clone,
+    I: DoubleEndedIterator + Clone,
+{
+    macro_rules! check_specialized {
+        ($src:expr, |$it:pat| $closure:expr) => {
+            // Many iterators special-case the first elements, so we test specializations for iterators that have already been advanced.
+            let mut src = $src.clone();
+            for step in 0..8 {
+                let $it = src.clone();
+                let v1 = $closure;
+                let $it = Unspecialized(src.clone());
+                let v2 = $closure;
+                assert_eq!(v1, v2);
+                if step % 2 == 0 {
+                    src.next();
+                } else {
+                    src.next_back();
+                }
+            }
+        }
+    }
+    check_specialized!(it, |i| {
+        let mut parameters_from_rfold = vec![];
+        let rfold_result = i.rfold(vec![], |mut acc, v: I::Item| {
+            parameters_from_rfold.push((acc.clone(), v.clone()));
+            acc.push(v);
+            acc
+        });
+        (parameters_from_rfold, rfold_result)
+    });
+    let size = it.clone().count();
+    for n in 0..size + 2 {
+        check_specialized!(it, |mut i| i.nth_back(n));
+    }
+}
+
+quickcheck! {
+    fn interleave(v: Vec<u8>, w: Vec<u8>) -> () {
+        test_specializations(&v.iter().interleave(w.iter()));
+    }
+
+    fn interleave_shortest(v: Vec<u8>, w: Vec<u8>) -> () {
+        test_specializations(&v.iter().interleave_shortest(w.iter()));
+    }
+
+    fn batching(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().batching(Iterator::next));
+    }
+
+    fn tuple_windows(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().tuple_windows::<(_,)>());
+        test_specializations(&v.iter().tuple_windows::<(_, _)>());
+        test_specializations(&v.iter().tuple_windows::<(_, _, _)>());
+    }
+
+    fn circular_tuple_windows(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().circular_tuple_windows::<(_,)>());
+        test_specializations(&v.iter().circular_tuple_windows::<(_, _)>());
+        test_specializations(&v.iter().circular_tuple_windows::<(_, _, _)>());
+    }
+
+    fn tuples(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().tuples::<(_,)>());
+        test_specializations(&v.iter().tuples::<(_, _)>());
+        test_specializations(&v.iter().tuples::<(_, _, _)>());
+    }
+
+    fn cartesian_product(a: Vec<u8>, b: Vec<u8>) -> TestResult {
+        if a.len() * b.len() > 100 {
+            return TestResult::discard();
+        }
+        test_specializations(&a.iter().cartesian_product(&b));
+        TestResult::passed()
+    }
+
+    fn multi_cartesian_product(a: Vec<u8>, b: Vec<u8>, c: Vec<u8>) -> TestResult {
+        if a.len() * b.len() * c.len() > 100 {
+            return TestResult::discard();
+        }
+        test_specializations(&vec![a, b, c].into_iter().multi_cartesian_product());
+        TestResult::passed()
+    }
+
+    fn coalesce(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().coalesce(|x, y| if x == y { Ok(x) } else { Err((x, y)) }))
+    }
+
+    fn dedup(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().dedup())
+    }
+
+    fn dedup_by(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().dedup_by(PartialOrd::ge))
+    }
+
+    fn dedup_with_count(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().dedup_with_count())
+    }
+
+    fn dedup_by_with_count(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().dedup_by_with_count(PartialOrd::ge))
+    }
+
+    fn duplicates(v: Vec<u8>) -> () {
+        let it = v.iter().duplicates();
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn duplicates_by(v: Vec<u8>) -> () {
+        let it = v.iter().duplicates_by(|x| *x % 10);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn unique(v: Vec<u8>) -> () {
+        let it = v.iter().unique();
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn unique_by(v: Vec<u8>) -> () {
+        let it = v.iter().unique_by(|x| *x % 50);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn take_while_inclusive(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().copied().take_while_inclusive(|&x| x < 100));
+    }
+
+    fn while_some(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().map(|&x| if x < 100 { Some(2 * x) } else { None }).while_some());
+    }
+
+    fn pad_using(v: Vec<u8>) -> () {
+        use std::convert::TryFrom;
+        let it = v.iter().copied().pad_using(10, |i| u8::try_from(5 * i).unwrap_or(u8::MAX));
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn with_position(v: Vec<u8>) -> () {
+        test_specializations(&v.iter().with_position());
+    }
+
+    fn positions(v: Vec<u8>) -> () {
+        let it = v.iter().positions(|x| x % 5 == 0);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn update(v: Vec<u8>) -> () {
+        let it = v.iter().copied().update(|x| *x = x.wrapping_mul(7));
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn tuple_combinations(v: Vec<u8>) -> TestResult {
+        if v.len() > 10 {
+            return TestResult::discard();
+        }
+        test_specializations(&v.iter().tuple_combinations::<(_,)>());
+        test_specializations(&v.iter().tuple_combinations::<(_, _)>());
+        test_specializations(&v.iter().tuple_combinations::<(_, _, _)>());
+        TestResult::passed()
+    }
+
+    fn intersperse(v: Vec<u8>) -> () {
+        test_specializations(&v.into_iter().intersperse(0));
+    }
+
+    fn intersperse_with(v: Vec<u8>) -> () {
+        test_specializations(&v.into_iter().intersperse_with(|| 0));
+    }
+
+    fn array_combinations(v: Vec<u8>) -> TestResult {
+        if v.len() > 10 {
+            return TestResult::discard();
+        }
+        test_specializations(&v.iter().array_combinations::<1>());
+        test_specializations(&v.iter().array_combinations::<2>());
+        test_specializations(&v.iter().array_combinations::<3>());
+        TestResult::passed()
+    }
+
+    fn combinations(a: Vec<u8>, n: u8) -> TestResult {
+        if n > 3 || a.len() > 8 {
+            return TestResult::discard();
+        }
+        test_specializations(&a.iter().combinations(n as usize));
+        TestResult::passed()
+    }
+
+    fn combinations_with_replacement(a: Vec<u8>, n: u8) -> TestResult {
+        if n > 3 || a.len() > 7 {
+            return TestResult::discard();
+        }
+        test_specializations(&a.iter().combinations_with_replacement(n as usize));
+        TestResult::passed()
+    }
+
+    fn permutations(a: Vec<u8>, n: u8) -> TestResult {
+        if n > 3 || a.len() > 8 {
+            return TestResult::discard();
+        }
+        test_specializations(&a.iter().permutations(n as usize));
+        TestResult::passed()
+    }
+
+    fn powerset(a: Vec<u8>) -> TestResult {
+        if a.len() > 6 {
+            return TestResult::discard();
+        }
+        test_specializations(&a.iter().powerset());
+        TestResult::passed()
+    }
+
+    fn zip_longest(a: Vec<u8>, b: Vec<u8>) -> () {
+        let it = a.into_iter().zip_longest(b);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn zip_eq(a: Vec<u8>) -> () {
+        test_specializations(&a.iter().zip_eq(a.iter().rev()))
+    }
+
+    fn multizip(a: Vec<u8>) -> () {
+        let it = itertools::multizip((a.iter(), a.iter().rev(), a.iter().take(50)));
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn izip(a: Vec<u8>, b: Vec<u8>) -> () {
+        test_specializations(&itertools::izip!(b.iter(), a, b.iter().rev()));
+    }
+
+    fn iproduct(a: Vec<u8>, b: Vec<u8>, c: Vec<u8>) -> TestResult {
+        if a.len() * b.len() * c.len() > 200 {
+            return TestResult::discard();
+        }
+        test_specializations(&itertools::iproduct!(a, b.iter(), c));
+        TestResult::passed()
+    }
+
+    fn repeat_n(element: i8, n: u8) -> () {
+        let it = itertools::repeat_n(element, n as usize);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn exactly_one_error(v: Vec<u8>) -> TestResult {
+        // Use `at_most_one` would be similar.
+        match v.iter().exactly_one() {
+            Ok(_) => TestResult::discard(),
+            Err(it) => {
+                test_specializations(&it);
+                TestResult::passed()
+            }
+        }
+    }
+}
+
+quickcheck! {
+    fn put_back_qc(test_vec: Vec<i32>) -> () {
+        test_specializations(&itertools::put_back(test_vec.iter()));
+        let mut pb = itertools::put_back(test_vec.into_iter());
+        pb.put_back(1);
+        test_specializations(&pb);
+    }
+
+    fn put_back_n(v: Vec<u8>, n: u8) -> () {
+        let mut it = itertools::put_back_n(v);
+        for k in 0..n {
+            it.put_back(k);
+        }
+        test_specializations(&it);
+    }
+
+    fn multipeek(v: Vec<u8>, n: u8) -> () {
+        let mut it = v.into_iter().multipeek();
+        for _ in 0..n {
+            it.peek();
+        }
+        test_specializations(&it);
+    }
+
+    fn peek_nth_with_peek(v: Vec<u8>, n: u8) -> () {
+        let mut it = itertools::peek_nth(v);
+        for _ in 0..n {
+            it.peek();
+        }
+        test_specializations(&it);
+    }
+
+    fn peek_nth_with_peek_nth(v: Vec<u8>, n: u8) -> () {
+        let mut it = itertools::peek_nth(v);
+        it.peek_nth(n as usize);
+        test_specializations(&it);
+    }
+
+    fn peek_nth_with_peek_mut(v: Vec<u8>, n: u8) -> () {
+        let mut it = itertools::peek_nth(v);
+        for _ in 0..n {
+            if let Some(x) = it.peek_mut() {
+                *x = x.wrapping_add(50);
+            }
+        }
+        test_specializations(&it);
+    }
+
+    fn peek_nth_with_peek_nth_mut(v: Vec<u8>, n: u8) -> () {
+        let mut it = itertools::peek_nth(v);
+        if let Some(x) = it.peek_nth_mut(n as usize) {
+            *x = x.wrapping_add(50);
+        }
+        test_specializations(&it);
+    }
+}
+
+quickcheck! {
+    fn merge(a: Vec<u8>, b: Vec<u8>) -> () {
+        test_specializations(&a.into_iter().merge(b))
+    }
+
+    fn merge_by(a: Vec<u8>, b: Vec<u8>) -> () {
+        test_specializations(&a.into_iter().merge_by(b, PartialOrd::ge))
+    }
+
+    fn merge_join_by_ordering(i1: Vec<u8>, i2: Vec<u8>) -> () {
+        test_specializations(&i1.into_iter().merge_join_by(i2, Ord::cmp));
+    }
+
+    fn merge_join_by_bool(i1: Vec<u8>, i2: Vec<u8>) -> () {
+        test_specializations(&i1.into_iter().merge_join_by(i2, PartialOrd::ge));
+    }
+
+    fn kmerge(a: Vec<i8>, b: Vec<i8>, c: Vec<i8>) -> () {
+        test_specializations(&vec![a, b, c]
+            .into_iter()
+            .map(|v| v.into_iter().sorted())
+            .kmerge());
+    }
+
+    fn kmerge_by(a: Vec<i8>, b: Vec<i8>, c: Vec<i8>) -> () {
+        test_specializations(&vec![a, b, c]
+            .into_iter()
+            .map(|v| v.into_iter().sorted_by_key(|a| a.abs()))
+            .kmerge_by(|a, b| a.abs() < b.abs()));
+    }
+}
+
+quickcheck! {
+    fn map_into(v: Vec<u8>) -> () {
+        let it = v.into_iter().map_into::<u32>();
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn map_ok(v: Vec<Result<u8, char>>) -> () {
+        let it = v.into_iter().map_ok(|u| u.checked_add(1));
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn filter_ok(v: Vec<Result<u8, char>>) -> () {
+        let it = v.into_iter().filter_ok(|&i| i < 20);
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    fn filter_map_ok(v: Vec<Result<u8, char>>) -> () {
+        let it = v.into_iter().filter_map_ok(|i| if i < 20 { Some(i * 2) } else { None });
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+
+    // `SmallIter2<u8>` because `Vec<u8>` is too slow and we get bad coverage from a singleton like Option<u8>
+    fn flatten_ok(v: Vec<Result<SmallIter2<u8>, char>>) -> () {
+        let it = v.into_iter().flatten_ok();
+        test_specializations(&it);
+        test_double_ended_specializations(&it);
+    }
+}
+
+quickcheck! {
+    // TODO Replace this function by a normal call to test_specializations
+    fn process_results(v: Vec<Result<u8, u8>>) -> () {
+        helper(v.iter().copied());
+        helper(v.iter().copied().filter(Result::is_ok));
+
+        fn helper(it: impl DoubleEndedIterator<Item = Result<u8, u8>> + Clone) {
+            macro_rules! check_results_specialized {
+                ($src:expr, |$it:pat| $closure:expr) => {
+                    assert_eq!(
+                        itertools::process_results($src.clone(), |$it| $closure),
+                        itertools::process_results($src.clone(), |i| {
+                            let $it = Unspecialized(i);
+                            $closure
+                        }),
+                    )
+                }
+            }
+
+            check_results_specialized!(it, |i| i.count());
+            check_results_specialized!(it, |i| i.last());
+            check_results_specialized!(it, |i| i.collect::<Vec<_>>());
+            check_results_specialized!(it, |i| i.rev().collect::<Vec<_>>());
+            check_results_specialized!(it, |i| {
+                let mut parameters_from_fold = vec![];
+                let fold_result = i.fold(vec![], |mut acc, v| {
+                    parameters_from_fold.push((acc.clone(), v));
+                    acc.push(v);
+                    acc
+                });
+                (parameters_from_fold, fold_result)
+            });
+            check_results_specialized!(it, |i| {
+                let mut parameters_from_rfold = vec![];
+                let rfold_result = i.rfold(vec![], |mut acc, v| {
+                    parameters_from_rfold.push((acc.clone(), v));
+                    acc.push(v);
+                    acc
+                });
+                (parameters_from_rfold, rfold_result)
+            });
+            check_results_specialized!(it, |mut i| {
+                let mut parameters_from_all = vec![];
+                let first = i.next();
+                let all_result = i.all(|x| {
+                    parameters_from_all.push(x);
+                    Some(x)==first
+                });
+                (parameters_from_all, all_result)
+            });
+            let size = it.clone().count();
+            for n in 0..size + 2 {
+                check_results_specialized!(it, |mut i| i.nth(n));
+            }
+            for n in 0..size + 2 {
+                check_results_specialized!(it, |mut i| i.nth_back(n));
+            }
+        }
+    }
+}
+
+/// Like `VecIntoIter<T>` with maximum 2 elements.
+#[derive(Debug, Clone, Default)]
+enum SmallIter2<T> {
+    #[default]
+    Zero,
+    One(T),
+    Two(T, T),
+}
+
+impl<T: Arbitrary> Arbitrary for SmallIter2<T> {
+    fn arbitrary<G: quickcheck::Gen>(g: &mut G) -> Self {
+        match g.gen_range(0u8, 3) {
+            0 => Self::Zero,
+            1 => Self::One(T::arbitrary(g)),
+            2 => Self::Two(T::arbitrary(g), T::arbitrary(g)),
+            _ => unreachable!(),
+        }
+    }
+    // maybe implement shrink too, maybe not
+}
+
+impl<T> Iterator for SmallIter2<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match std::mem::take(self) {
+            Self::Zero => None,
+            Self::One(val) => Some(val),
+            Self::Two(val, second) => {
+                *self = Self::One(second);
+                Some(val)
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = match self {
+            Self::Zero => 0,
+            Self::One(_) => 1,
+            Self::Two(_, _) => 2,
+        };
+        (len, Some(len))
+    }
+}
+
+impl<T> DoubleEndedIterator for SmallIter2<T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        match std::mem::take(self) {
+            Self::Zero => None,
+            Self::One(val) => Some(val),
+            Self::Two(first, val) => {
+                *self = Self::One(first);
+                Some(val)
+            }
+        }
+    }
+}

vendor/itertools/tests/test_core.rs

@@ -0,0 +1,399 @@
+//! Licensed under the Apache License, Version 2.0
+//! https://www.apache.org/licenses/LICENSE-2.0 or the MIT license
+//! https://opensource.org/licenses/MIT, at your
+//! option. This file may not be copied, modified, or distributed
+//! except according to those terms.
+#![no_std]
+#![allow(deprecated)]
+
+use crate::it::chain;
+use crate::it::free::put_back;
+use crate::it::interleave;
+use crate::it::intersperse;
+use crate::it::intersperse_with;
+use crate::it::iproduct;
+use crate::it::izip;
+use crate::it::multizip;
+use crate::it::Itertools;
+use core::iter;
+use itertools as it;
+
+#[allow(dead_code)]
+fn get_esi_then_esi<I: ExactSizeIterator + Clone>(it: I) {
+    fn is_esi(_: impl ExactSizeIterator) {}
+    is_esi(it.clone().get(1..4));
+    is_esi(it.clone().get(1..=4));
+    is_esi(it.clone().get(1..));
+    is_esi(it.clone().get(..4));
+    is_esi(it.clone().get(..=4));
+    is_esi(it.get(..));
+}
+
+#[allow(dead_code)]
+fn get_dei_esi_then_dei_esi<I: DoubleEndedIterator + ExactSizeIterator + Clone>(it: I) {
+    fn is_dei_esi(_: impl DoubleEndedIterator + ExactSizeIterator) {}
+    is_dei_esi(it.clone().get(1..4));
+    is_dei_esi(it.clone().get(1..=4));
+    is_dei_esi(it.clone().get(1..));
+    is_dei_esi(it.clone().get(..4));
+    is_dei_esi(it.clone().get(..=4));
+    is_dei_esi(it.get(..));
+}
+
+#[test]
+fn get_1_max() {
+    let mut it = (0..5).get(1..=usize::MAX);
+    assert_eq!(it.next(), Some(1));
+    assert_eq!(it.next_back(), Some(4));
+}
+
+#[test]
+#[should_panic]
+fn get_full_range_inclusive() {
+    let _it = (0..5).get(0..=usize::MAX);
+}
+
+#[test]
+fn product0() {
+    let mut prod = iproduct!();
+    assert_eq!(prod.next(), Some(()));
+    assert!(prod.next().is_none());
+}
+
+#[test]
+fn iproduct1() {
+    let s = "αβ";
+
+    let mut prod = iproduct!(s.chars());
+    assert_eq!(prod.next(), Some(('α',)));
+    assert_eq!(prod.next(), Some(('β',)));
+    assert!(prod.next().is_none());
+}
+
+#[test]
+fn product2() {
+    let s = "αβ";
+
+    let mut prod = iproduct!(s.chars(), 0..2);
+    assert!(prod.next() == Some(('α', 0)));
+    assert!(prod.next() == Some(('α', 1)));
+    assert!(prod.next() == Some(('β', 0)));
+    assert!(prod.next() == Some(('β', 1)));
+    assert!(prod.next().is_none());
+}
+
+#[test]
+fn product_temporary() {
+    for (_x, _y, _z) in iproduct!(
+        [0, 1, 2].iter().cloned(),
+        [0, 1, 2].iter().cloned(),
+        [0, 1, 2].iter().cloned()
+    ) {
+        // ok
+    }
+}
+
+#[test]
+fn izip_macro() {
+    let mut zip = izip!(2..3);
+    assert!(zip.next() == Some(2));
+    assert!(zip.next().is_none());
+
+    let mut zip = izip!(0..3, 0..2, 0..2i8);
+    for i in 0..2 {
+        assert!((i as usize, i, i as i8) == zip.next().unwrap());
+    }
+    assert!(zip.next().is_none());
+
+    let xs: [isize; 0] = [];
+    let mut zip = izip!(0..3, 0..2, 0..2i8, &xs);
+    assert!(zip.next().is_none());
+}
+
+#[test]
+fn izip2() {
+    let _zip1: iter::Zip<_, _> = izip!(1.., 2..);
+    let _zip2: iter::Zip<_, _> = izip!(1.., 2..,);
+}
+
+#[test]
+fn izip3() {
+    let mut zip: iter::Map<iter::Zip<_, _>, _> = izip!(0..3, 0..2, 0..2i8);
+    for i in 0..2 {
+        assert!((i as usize, i, i as i8) == zip.next().unwrap());
+    }
+    assert!(zip.next().is_none());
+}
+
+#[test]
+fn multizip3() {
+    let mut zip = multizip((0..3, 0..2, 0..2i8));
+    for i in 0..2 {
+        assert!((i as usize, i, i as i8) == zip.next().unwrap());
+    }
+    assert!(zip.next().is_none());
+
+    let xs: [isize; 0] = [];
+    let mut zip = multizip((0..3, 0..2, 0..2i8, xs.iter()));
+    assert!(zip.next().is_none());
+
+    for (_, _, _, _, _) in multizip((0..3, 0..2, xs.iter(), &xs, xs.to_vec())) {
+        /* test compiles */
+    }
+}
+
+#[test]
+fn chain_macro() {
+    let mut chain = chain!(2..3);
+    assert!(chain.next() == Some(2));
+    assert!(chain.next().is_none());
+
+    let mut chain = chain!(0..2, 2..3, 3..5i8);
+    for i in 0..5i8 {
+        assert_eq!(Some(i), chain.next());
+    }
+    assert!(chain.next().is_none());
+
+    let mut chain = chain!();
+    assert_eq!(chain.next(), Option::<()>::None);
+}
+
+#[test]
+fn chain2() {
+    let _ = chain!(1.., 2..);
+    let _ = chain!(1.., 2..,);
+}
+
+#[test]
+fn write_to() {
+    let xs = [7, 9, 8];
+    let mut ys = [0; 5];
+    let cnt = ys.iter_mut().set_from(xs.iter().copied());
+    assert!(cnt == xs.len());
+    assert!(ys == [7, 9, 8, 0, 0]);
+
+    let cnt = ys.iter_mut().set_from(0..10);
+    assert!(cnt == ys.len());
+    assert!(ys == [0, 1, 2, 3, 4]);
+}
+
+#[test]
+fn test_interleave() {
+    let xs: [u8; 0] = [];
+    let ys = [7u8, 9, 8, 10];
+    let zs = [2u8, 77];
+    let it = interleave(xs.iter(), ys.iter());
+    it::assert_equal(it, ys.iter());
+
+    let rs = [7u8, 2, 9, 77, 8, 10];
+    let it = interleave(ys.iter(), zs.iter());
+    it::assert_equal(it, rs.iter());
+}
+
+#[test]
+fn test_intersperse() {
+    let xs = [1u8, 2, 3];
+    let ys = [1u8, 0, 2, 0, 3];
+    let it = intersperse(&xs, &0);
+    it::assert_equal(it, ys.iter());
+}
+
+#[test]
+fn test_intersperse_with() {
+    let xs = [1u8, 2, 3];
+    let ys = [1u8, 10, 2, 10, 3];
+    let i = 10;
+    let it = intersperse_with(&xs, || &i);
+    it::assert_equal(it, ys.iter());
+}
+
+#[test]
+fn dropping() {
+    let xs = [1, 2, 3];
+    let mut it = xs.iter().dropping(2);
+    assert_eq!(it.next(), Some(&3));
+    assert!(it.next().is_none());
+    let mut it = xs.iter().dropping(5);
+    assert!(it.next().is_none());
+}
+
+#[test]
+fn batching() {
+    let xs = [0, 1, 2, 1, 3];
+    let ys = [(0, 1), (2, 1)];
+
+    // An iterator that gathers elements up in pairs
+    let pit = xs
+        .iter()
+        .cloned()
+        .batching(|it| it.next().and_then(|x| it.next().map(|y| (x, y))));
+    it::assert_equal(pit, ys.iter().cloned());
+}
+
+#[test]
+fn test_put_back() {
+    let xs = [0, 1, 1, 1, 2, 1, 3, 3];
+    let mut pb = put_back(xs.iter().cloned());
+    pb.next();
+    pb.put_back(1);
+    pb.put_back(0);
+    it::assert_equal(pb, xs.iter().cloned());
+}
+
+#[test]
+fn merge() {
+    it::assert_equal((0..10).step_by(2).merge((1..10).step_by(2)), 0..10);
+}
+
+#[test]
+fn repeatn() {
+    let s = "α";
+    let mut it = it::repeat_n(s, 3);
+    assert_eq!(it.len(), 3);
+    assert_eq!(it.next(), Some(s));
+    assert_eq!(it.next(), Some(s));
+    assert_eq!(it.next(), Some(s));
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+}
+
+#[test]
+fn count_clones() {
+    // Check that RepeatN only clones N - 1 times.
+
+    use core::cell::Cell;
+    #[derive(PartialEq, Debug)]
+    struct Foo {
+        n: Cell<usize>,
+    }
+
+    impl Clone for Foo {
+        fn clone(&self) -> Self {
+            let n = self.n.get();
+            self.n.set(n + 1);
+            Self {
+                n: Cell::new(n + 1),
+            }
+        }
+    }
+
+    for n in 0..10 {
+        let f = Foo { n: Cell::new(0) };
+        let it = it::repeat_n(f, n);
+        // drain it
+        let last = it.last();
+        if n == 0 {
+            assert_eq!(last, None);
+        } else {
+            assert_eq!(
+                last,
+                Some(Foo {
+                    n: Cell::new(n - 1)
+                })
+            );
+        }
+    }
+}
+
+#[test]
+fn part() {
+    let mut data = [7, 1, 1, 9, 1, 1, 3];
+    let i = it::partition(&mut data, |elt| *elt >= 3);
+    assert_eq!(i, 3);
+    assert_eq!(data, [7, 3, 9, 1, 1, 1, 1]);
+
+    let i = it::partition(&mut data, |elt| *elt == 1);
+    assert_eq!(i, 4);
+    assert_eq!(data, [1, 1, 1, 1, 9, 3, 7]);
+
+    let mut data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+    let i = it::partition(&mut data, |elt| *elt % 3 == 0);
+    assert_eq!(i, 3);
+    assert_eq!(data, [9, 6, 3, 4, 5, 2, 7, 8, 1]);
+}
+
+#[test]
+fn tree_reduce() {
+    for i in 0..100 {
+        assert_eq!((0..i).tree_reduce(|x, y| x + y), (0..i).fold1(|x, y| x + y));
+    }
+}
+
+#[test]
+fn exactly_one() {
+    assert_eq!((0..10).filter(|&x| x == 2).exactly_one().unwrap(), 2);
+    assert!((0..10)
+        .filter(|&x| x > 1 && x < 4)
+        .exactly_one()
+        .unwrap_err()
+        .eq(2..4));
+    assert!((0..10)
+        .filter(|&x| x > 1 && x < 5)
+        .exactly_one()
+        .unwrap_err()
+        .eq(2..5));
+    assert!((0..10)
+        .filter(|&_| false)
+        .exactly_one()
+        .unwrap_err()
+        .eq(0..0));
+}
+
+#[test]
+fn at_most_one() {
+    assert_eq!((0..10).filter(|&x| x == 2).at_most_one().unwrap(), Some(2));
+    assert!((0..10)
+        .filter(|&x| x > 1 && x < 4)
+        .at_most_one()
+        .unwrap_err()
+        .eq(2..4));
+    assert!((0..10)
+        .filter(|&x| x > 1 && x < 5)
+        .at_most_one()
+        .unwrap_err()
+        .eq(2..5));
+    assert_eq!((0..10).filter(|&_| false).at_most_one().unwrap(), None);
+}
+
+#[test]
+fn sum1() {
+    let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    assert_eq!(v[..0].iter().cloned().sum1::<i32>(), None);
+    assert_eq!(v[1..2].iter().cloned().sum1::<i32>(), Some(1));
+    assert_eq!(v[1..3].iter().cloned().sum1::<i32>(), Some(3));
+    assert_eq!(v.iter().cloned().sum1::<i32>(), Some(55));
+}
+
+#[test]
+fn product1() {
+    let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    assert_eq!(v[..0].iter().cloned().product1::<i32>(), None);
+    assert_eq!(v[..1].iter().cloned().product1::<i32>(), Some(0));
+    assert_eq!(v[1..3].iter().cloned().product1::<i32>(), Some(2));
+    assert_eq!(v[1..5].iter().cloned().product1::<i32>(), Some(24));
+}
+
+#[test]
+fn next_array() {
+    let v = [1, 2, 3, 4, 5];
+    let mut iter = v.iter();
+    assert_eq!(iter.next_array(), Some([]));
+    assert_eq!(iter.next_array().map(|[&x, &y]| [x, y]), Some([1, 2]));
+    assert_eq!(iter.next_array().map(|[&x, &y]| [x, y]), Some([3, 4]));
+    assert_eq!(iter.next_array::<2>(), None);
+}
+
+#[test]
+fn collect_array() {
+    let v = [1, 2];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_array(), Some([1, 2]));
+
+    let v = [1];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_array::<2>(), None);
+
+    let v = [1, 2, 3];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_array::<2>(), None);
+}

vendor/itertools/tests/tuples.rs

@@ -0,0 +1,86 @@
+use itertools::Itertools;
+
+#[test]
+fn tuples() {
+    let v = [1, 2, 3, 4, 5];
+    let mut iter = v.iter().cloned().tuples();
+    assert_eq!(Some((1,)), iter.next());
+    assert_eq!(Some((2,)), iter.next());
+    assert_eq!(Some((3,)), iter.next());
+    assert_eq!(Some((4,)), iter.next());
+    assert_eq!(Some((5,)), iter.next());
+    assert_eq!(None, iter.next());
+    assert_eq!(None, iter.into_buffer().next());
+
+    let mut iter = v.iter().cloned().tuples();
+    assert_eq!(Some((1, 2)), iter.next());
+    assert_eq!(Some((3, 4)), iter.next());
+    assert_eq!(None, iter.next());
+    itertools::assert_equal(vec![5], iter.into_buffer());
+
+    let mut iter = v.iter().cloned().tuples();
+    assert_eq!(Some((1, 2, 3)), iter.next());
+    assert_eq!(None, iter.next());
+    itertools::assert_equal(vec![4, 5], iter.into_buffer());
+
+    let mut iter = v.iter().cloned().tuples();
+    assert_eq!(Some((1, 2, 3, 4)), iter.next());
+    assert_eq!(None, iter.next());
+    itertools::assert_equal(vec![5], iter.into_buffer());
+}
+
+#[test]
+fn tuple_windows() {
+    let v = [1, 2, 3, 4, 5];
+
+    let mut iter = v.iter().cloned().tuple_windows();
+    assert_eq!(Some((1,)), iter.next());
+    assert_eq!(Some((2,)), iter.next());
+    assert_eq!(Some((3,)), iter.next());
+
+    let mut iter = v.iter().cloned().tuple_windows();
+    assert_eq!(Some((1, 2)), iter.next());
+    assert_eq!(Some((2, 3)), iter.next());
+    assert_eq!(Some((3, 4)), iter.next());
+    assert_eq!(Some((4, 5)), iter.next());
+    assert_eq!(None, iter.next());
+
+    let mut iter = v.iter().cloned().tuple_windows();
+    assert_eq!(Some((1, 2, 3)), iter.next());
+    assert_eq!(Some((2, 3, 4)), iter.next());
+    assert_eq!(Some((3, 4, 5)), iter.next());
+    assert_eq!(None, iter.next());
+
+    let mut iter = v.iter().cloned().tuple_windows();
+    assert_eq!(Some((1, 2, 3, 4)), iter.next());
+    assert_eq!(Some((2, 3, 4, 5)), iter.next());
+    assert_eq!(None, iter.next());
+
+    let v = [1, 2, 3];
+    let mut iter = v.iter().cloned().tuple_windows::<(_, _, _, _)>();
+    assert_eq!(None, iter.next());
+}
+
+#[test]
+fn next_tuple() {
+    let v = [1, 2, 3, 4, 5];
+    let mut iter = v.iter();
+    assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((1, 2)));
+    assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((3, 4)));
+    assert_eq!(iter.next_tuple::<(_, _)>(), None);
+}
+
+#[test]
+fn collect_tuple() {
+    let v = [1, 2];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_tuple(), Some((1, 2)));
+
+    let v = [1];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_tuple::<(_, _)>(), None);
+
+    let v = [1, 2, 3];
+    let iter = v.iter().cloned();
+    assert_eq!(iter.collect_tuple::<(_, _)>(), None);
+}

vendor/itertools/tests/zip.rs

@@ -0,0 +1,56 @@
+use itertools::multizip;
+use itertools::EitherOrBoth::{Both, Left, Right};
+use itertools::Itertools;
+
+#[test]
+fn zip_longest_fused() {
+    let a = [Some(1), None, Some(3), Some(4)];
+    let b = [1, 2, 3];
+
+    let unfused = a
+        .iter()
+        .batching(|it| *it.next().unwrap())
+        .zip_longest(b.iter().cloned());
+    itertools::assert_equal(unfused, vec![Both(1, 1), Right(2), Right(3)]);
+}
+
+#[test]
+fn test_zip_longest_size_hint() {
+    let c = (1..10).cycle();
+    let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+    let v2 = &[10, 11, 12];
+
+    assert_eq!(c.zip_longest(v.iter()).size_hint(), (usize::MAX, None));
+
+    assert_eq!(v.iter().zip_longest(v2.iter()).size_hint(), (10, Some(10)));
+}
+
+#[test]
+fn test_double_ended_zip_longest() {
+    let xs = [1, 2, 3, 4, 5, 6];
+    let ys = [1, 2, 3, 7];
+    let a = xs.iter().copied();
+    let b = ys.iter().copied();
+    let mut it = a.zip_longest(b);
+    assert_eq!(it.next(), Some(Both(1, 1)));
+    assert_eq!(it.next(), Some(Both(2, 2)));
+    assert_eq!(it.next_back(), Some(Left(6)));
+    assert_eq!(it.next_back(), Some(Left(5)));
+    assert_eq!(it.next_back(), Some(Both(4, 7)));
+    assert_eq!(it.next(), Some(Both(3, 3)));
+    assert_eq!(it.next(), None);
+}
+
+#[test]
+fn test_double_ended_zip() {
+    let xs = [1, 2, 3, 4, 5, 6];
+    let ys = [1, 2, 3, 7];
+    let a = xs.iter().copied();
+    let b = ys.iter().copied();
+    let mut it = multizip((a, b));
+    assert_eq!(it.next_back(), Some((4, 7)));
+    assert_eq!(it.next_back(), Some((3, 3)));
+    assert_eq!(it.next_back(), Some((2, 2)));
+    assert_eq!(it.next_back(), Some((1, 1)));
+    assert_eq!(it.next_back(), None);
+}