Add unit tests for array::IntoIter

Many tests are based on tests by Josh Stone <cuviper@gmail.com>

src/libcore/tests/array.rs

@@ -1,4 +1,4 @@
-use core::array::FixedSizeArray;
+use core::array::{FixedSizeArray, IntoIter};
 use core::convert::TryFrom;
 
 #[test]
@@ -40,3 +40,208 @@ fn array_try_from() {
         30 31 32
     }
 }
+
+
+#[test]
+fn iterator_collect() {
+    let arr = [0, 1, 2, 5, 9];
+    let v: Vec<_> = IntoIter::new(arr.clone()).collect();
+    assert_eq!(&arr[..], &v[..]);
+}
+
+#[test]
+fn iterator_rev_collect() {
+    let arr = [0, 1, 2, 5, 9];
+    let v: Vec<_> = IntoIter::new(arr.clone()).rev().collect();
+    assert_eq!(&v[..], &[9, 5, 2, 1, 0]);
+}
+
+#[test]
+fn iterator_nth() {
+    let v = [0, 1, 2, 3, 4];
+    for i in 0..v.len() {
+        assert_eq!(IntoIter::new(v.clone()).nth(i).unwrap(), v[i]);
+    }
+    assert_eq!(IntoIter::new(v.clone()).nth(v.len()), None);
+
+    let mut iter = IntoIter::new(v);
+    assert_eq!(iter.nth(2).unwrap(), v[2]);
+    assert_eq!(iter.nth(1).unwrap(), v[4]);
+}
+
+#[test]
+fn iterator_last() {
+    let v = [0, 1, 2, 3, 4];
+    assert_eq!(IntoIter::new(v).last().unwrap(), 4);
+    assert_eq!(IntoIter::new([0]).last().unwrap(), 0);
+
+    let mut it = IntoIter::new([0, 9, 2, 4]);
+    assert_eq!(it.next_back(), Some(4));
+    assert_eq!(it.last(), Some(2));
+}
+
+#[test]
+fn iterator_clone() {
+    let mut it = IntoIter::new([0, 2, 4, 6, 8]);
+    assert_eq!(it.next(), Some(0));
+    assert_eq!(it.next_back(), Some(8));
+    let mut clone = it.clone();
+    assert_eq!(it.next_back(), Some(6));
+    assert_eq!(clone.next_back(), Some(6));
+    assert_eq!(it.next_back(), Some(4));
+    assert_eq!(clone.next_back(), Some(4));
+    assert_eq!(it.next(), Some(2));
+    assert_eq!(clone.next(), Some(2));
+}
+
+#[test]
+fn iterator_fused() {
+    let mut it = IntoIter::new([0, 9, 2]);
+    assert_eq!(it.next(), Some(0));
+    assert_eq!(it.next(), Some(9));
+    assert_eq!(it.next(), Some(2));
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+    assert_eq!(it.next(), None);
+}
+
+#[test]
+fn iterator_len() {
+    let mut it = IntoIter::new([0, 1, 2, 5, 9]);
+    assert_eq!(it.size_hint(), (5, Some(5)));
+    assert_eq!(it.len(), 5);
+    assert_eq!(it.is_empty(), false);
+
+    assert_eq!(it.next(), Some(0));
+    assert_eq!(it.size_hint(), (4, Some(4)));
+    assert_eq!(it.len(), 4);
+    assert_eq!(it.is_empty(), false);
+
+    assert_eq!(it.next_back(), Some(9));
+    assert_eq!(it.size_hint(), (3, Some(3)));
+    assert_eq!(it.len(), 3);
+    assert_eq!(it.is_empty(), false);
+
+    // Empty
+    let it = IntoIter::new([] as [String; 0]);
+    assert_eq!(it.size_hint(), (0, Some(0)));
+    assert_eq!(it.len(), 0);
+    assert_eq!(it.is_empty(), true);
+}
+
+#[test]
+fn iterator_count() {
+    let v = [0, 1, 2, 3, 4];
+    assert_eq!(IntoIter::new(v.clone()).count(), 5);
+
+    let mut iter2 = IntoIter::new(v);
+    iter2.next();
+    iter2.next();
+    assert_eq!(iter2.count(), 3);
+}
+
+#[test]
+fn iterator_flat_map() {
+    assert!((0..5).flat_map(|i| IntoIter::new([2 * i, 2 * i + 1])).eq(0..10));
+}
+
+#[test]
+fn iterator_debug() {
+    let arr = [0, 1, 2, 5, 9];
+    assert_eq!(
+        format!("{:?}", IntoIter::new(arr)),
+        "IntoIter([0, 1, 2, 5, 9])",
+    );
+}
+
+#[test]
+fn iterator_drops() {
+    use core::cell::Cell;
+
+    // This test makes sure the correct number of elements are dropped. The `R`
+    // type is just a reference to a `Cell` that is incremented when an `R` is
+    // dropped.
+
+    #[derive(Clone)]
+    struct Foo<'a>(&'a Cell<usize>);
+
+    impl Drop for Foo<'_> {
+       fn drop(&mut self) {
+            self.0.set(self.0.get() + 1);
+        }
+    }
+
+    fn five(i: &Cell<usize>) -> [Foo<'_>; 5] {
+        // This is somewhat verbose because `Foo` does not implement `Copy`
+        // since it implements `Drop`. Consequently, we cannot write
+        // `[Foo(i); 5]`.
+        [Foo(i), Foo(i), Foo(i), Foo(i), Foo(i)]
+    }
+
+    // Simple: drop new iterator.
+    let i = Cell::new(0);
+    {
+        IntoIter::new(five(&i));
+    }
+    assert_eq!(i.get(), 5);
+
+    // Call `next()` once.
+    let i = Cell::new(0);
+    {
+        let mut iter = IntoIter::new(five(&i));
+        let _x = iter.next();
+        assert_eq!(i.get(), 0);
+        assert_eq!(iter.count(), 4);
+        assert_eq!(i.get(), 4);
+    }
+    assert_eq!(i.get(), 5);
+
+    // Check `clone` and calling `next`/`next_back`.
+    let i = Cell::new(0);
+    {
+        let mut iter = IntoIter::new(five(&i));
+        iter.next();
+        assert_eq!(i.get(), 1);
+        iter.next_back();
+        assert_eq!(i.get(), 2);
+
+        let mut clone = iter.clone();
+        assert_eq!(i.get(), 2);
+
+        iter.next();
+        assert_eq!(i.get(), 3);
+
+        clone.next();
+        assert_eq!(i.get(), 4);
+
+        assert_eq!(clone.count(), 2);
+        assert_eq!(i.get(), 6);
+    }
+    assert_eq!(i.get(), 8);
+
+    // Check via `nth`.
+    let i = Cell::new(0);
+    {
+        let mut iter = IntoIter::new(five(&i));
+        let _x = iter.nth(2);
+        assert_eq!(i.get(), 2);
+        let _y = iter.last();
+        assert_eq!(i.get(), 3);
+    }
+    assert_eq!(i.get(), 5);
+
+    // Check every element.
+    let i = Cell::new(0);
+    for (index, _x) in IntoIter::new(five(&i)).enumerate() {
+        assert_eq!(i.get(), index);
+    }
+    assert_eq!(i.get(), 5);
+
+    let i = Cell::new(0);
+    for (index, _x) in IntoIter::new(five(&i)).rev().enumerate() {
+        assert_eq!(i.get(), index);
+    }
+    assert_eq!(i.get(), 5);
+}

src/libcore/tests/lib.rs

@@ -31,6 +31,7 @@
 #![feature(slice_partition_dedup)]
 #![feature(int_error_matching)]
 #![feature(const_fn)]
+#![feature(array_value_iter)]
 #![feature(iter_partition_in_place)]
 #![feature(iter_is_partitioned)]
 #![feature(iter_order_by)]