1 files changed, 27 insertions, 0 deletions
diff --git a/library/core/tests/iter/adapters/map.rs b/library/core/tests/iter/adapters/map.rs
new file mode 100644
index 000000000..77ce3819b
--- /dev/null
+++ b/library/core/tests/iter/adapters/map.rs
@@ -0,0 +1,27 @@
+use core::iter::*;
+
+#[test]
+fn test_map_try_folds() {
+    let f = &|acc, x| i32::checked_add(2 * acc, x);
+    assert_eq!((0..10).map(|x| x + 3).try_fold(7, f), (3..13).try_fold(7, f));
+    assert_eq!((0..10).map(|x| x + 3).try_rfold(7, f), (3..13).try_rfold(7, f));
+
+    let mut iter = (0..40).map(|x| x + 10);
+    assert_eq!(iter.try_fold(0, i8::checked_add), None);
+    assert_eq!(iter.next(), Some(20));
+    assert_eq!(iter.try_rfold(0, i8::checked_add), None);
+    assert_eq!(iter.next_back(), Some(46));
+}
+
+#[test]
+fn test_double_ended_map() {
+    let xs = [1, 2, 3, 4, 5, 6];
+    let mut it = xs.iter().map(|&x| x * -1);
+    assert_eq!(it.next(), Some(-1));
+    assert_eq!(it.next(), Some(-2));
+    assert_eq!(it.next_back(), Some(-6));
+    assert_eq!(it.next_back(), Some(-5));
+    assert_eq!(it.next(), Some(-3));
+    assert_eq!(it.next_back(), Some(-4));
+    assert_eq!(it.next(), None);
+}