1 files changed, 21 insertions, 20 deletions

diff --git a/library/core/tests/iter/adapters/chain.rs b/library/core/tests/iter/adapters/chain.rs
index f419f9cec..175a1b638 100644
--- a/library/core/tests/iter/adapters/chain.rs
+++ b/library/core/tests/iter/adapters/chain.rs
@@ -1,5 +1,6 @@
 use super::*;
 use core::iter::*;
+use core::num::NonZeroUsize;
 
 #[test]
 fn test_iterator_chain() {
@@ -31,28 +32,28 @@ fn test_iterator_chain_advance_by() {
 
         for i in 0..xs.len() {
             let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys));
-            iter.advance_by(i).unwrap();
+            assert_eq!(iter.advance_by(i), Ok(()));
             assert_eq!(iter.next(), Some(&xs[i]));
-            assert_eq!(iter.advance_by(100), Err(len - i - 1));
-            iter.advance_by(0).unwrap();
+            assert_eq!(iter.advance_by(100), Err(NonZeroUsize::new(100 - (len - i - 1)).unwrap()));
+            assert_eq!(iter.advance_by(0), Ok(()));
         }
 
         for i in 0..ys.len() {
             let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys));
-            iter.advance_by(xs.len() + i).unwrap();
+            assert_eq!(iter.advance_by(xs.len() + i), Ok(()));
             assert_eq!(iter.next(), Some(&ys[i]));
-            assert_eq!(iter.advance_by(100), Err(ys.len() - i - 1));
-            iter.advance_by(0).unwrap();
+            assert_eq!(iter.advance_by(100), Err(NonZeroUsize::new(100 - (ys.len() - i - 1)).unwrap()));
+            assert_eq!(iter.advance_by(0), Ok(()));
         }
 
         let mut iter = xs.iter().chain(ys);
-        iter.advance_by(len).unwrap();
+        assert_eq!(iter.advance_by(len), Ok(()));
         assert_eq!(iter.next(), None);
-        iter.advance_by(0).unwrap();
+        assert_eq!(iter.advance_by(0), Ok(()));
 
         let mut iter = xs.iter().chain(ys);
-        assert_eq!(iter.advance_by(len + 1), Err(len));
-        iter.advance_by(0).unwrap();
+        assert_eq!(iter.advance_by(len + 1), Err(NonZeroUsize::new(1).unwrap()));
+        assert_eq!(iter.advance_by(0), Ok(()));
     }
 
     test_chain(&[], &[]);
@@ -68,28 +69,28 @@ fn test_iterator_chain_advance_back_by() {
 
         for i in 0..ys.len() {
             let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys));
-            iter.advance_back_by(i).unwrap();
+            assert_eq!(iter.advance_back_by(i), Ok(()));
             assert_eq!(iter.next_back(), Some(&ys[ys.len() - i - 1]));
-            assert_eq!(iter.advance_back_by(100), Err(len - i - 1));
-            iter.advance_back_by(0).unwrap();
+            assert_eq!(iter.advance_back_by(100), Err(NonZeroUsize::new(100 - (len - i - 1)).unwrap()));
+            assert_eq!(iter.advance_back_by(0), Ok(()));
         }
 
         for i in 0..xs.len() {
             let mut iter = Unfuse::new(xs).chain(Unfuse::new(ys));
-            iter.advance_back_by(ys.len() + i).unwrap();
+            assert_eq!(iter.advance_back_by(ys.len() + i), Ok(()));
             assert_eq!(iter.next_back(), Some(&xs[xs.len() - i - 1]));
-            assert_eq!(iter.advance_back_by(100), Err(xs.len() - i - 1));
-            iter.advance_back_by(0).unwrap();
+            assert_eq!(iter.advance_back_by(100), Err(NonZeroUsize::new(100 - (xs.len() - i - 1)).unwrap()));
+            assert_eq!(iter.advance_back_by(0), Ok(()));
         }
 
         let mut iter = xs.iter().chain(ys);
-        iter.advance_back_by(len).unwrap();
+        assert_eq!(iter.advance_back_by(len), Ok(()));
         assert_eq!(iter.next_back(), None);
-        iter.advance_back_by(0).unwrap();
+        assert_eq!(iter.advance_back_by(0), Ok(()));
 
         let mut iter = xs.iter().chain(ys);
-        assert_eq!(iter.advance_back_by(len + 1), Err(len));
-        iter.advance_back_by(0).unwrap();
+        assert_eq!(iter.advance_back_by(len + 1), Err(NonZeroUsize::new(1).unwrap()));
+        assert_eq!(iter.advance_back_by(0), Ok(()));
     }
 
     test_chain(&[], &[]);