Fix Iterator::advance_by contract inconsistency

[rust.git] / library / core / tests / iter / adapters / chain.rs

diff --git a/library/core/tests/iter/adapters/chain.rs b/library/core/tests/iter/adapters/chain.rs
index 4cd79687b53d4c372ace346ad2e67effc279ce91..f419f9cec12f8555df3281eae5019b75f4b88ea5 100644 (file)
--- a/library/core/tests/iter/adapters/chain.rs
+++ b/library/core/tests/iter/adapters/chain.rs
@@ -34,6 +34,7 @@ fn test_chain(xs: &[i32], ys: &[i32]) {
             iter.advance_by(i).unwrap();
             assert_eq!(iter.next(), Some(&xs[i]));
             assert_eq!(iter.advance_by(100), Err(len - i - 1));
+            iter.advance_by(0).unwrap();
         }
 
         for i in 0..ys.len() {
@@ -41,14 +42,17 @@ fn test_chain(xs: &[i32], ys: &[i32]) {
             iter.advance_by(xs.len() + i).unwrap();
             assert_eq!(iter.next(), Some(&ys[i]));
             assert_eq!(iter.advance_by(100), Err(ys.len() - i - 1));
+            iter.advance_by(0).unwrap();
         }
 
         let mut iter = xs.iter().chain(ys);
         iter.advance_by(len).unwrap();
         assert_eq!(iter.next(), None);
+        iter.advance_by(0).unwrap();
 
         let mut iter = xs.iter().chain(ys);
         assert_eq!(iter.advance_by(len + 1), Err(len));
+        iter.advance_by(0).unwrap();
     }
 
     test_chain(&[], &[]);
@@ -67,6 +71,7 @@ fn test_chain(xs: &[i32], ys: &[i32]) {
             iter.advance_back_by(i).unwrap();
             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();
         }
 
         for i in 0..xs.len() {
@@ -74,14 +79,17 @@ fn test_chain(xs: &[i32], ys: &[i32]) {
             iter.advance_back_by(ys.len() + i).unwrap();
             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();
         }
 
         let mut iter = xs.iter().chain(ys);
         iter.advance_back_by(len).unwrap();
         assert_eq!(iter.next_back(), None);
+        iter.advance_back_by(0).unwrap();
 
         let mut iter = xs.iter().chain(ys);
         assert_eq!(iter.advance_back_by(len + 1), Err(len));
+        iter.advance_back_by(0).unwrap();
     }
 
     test_chain(&[], &[]);