3 files changed, 44 insertions, 14 deletions
diff --git a/src/liballoc/tests/slice.rs b/src/liballoc/tests/slice.rs
index 7fa65a2144e..c53bf15f1bf 100644
--- a/src/liballoc/tests/slice.rs
+++ b/src/liballoc/tests/slice.rs
@@ -396,18 +396,44 @@ fn test_sort() {
     let mut rng = thread_rng();
 
     for len in (2..25).chain(500..510) {
-        for _ in 0..100 {
-            let mut v: Vec<_> = rng.gen_iter::<i32>().take(len).collect();
-            let mut v1 = v.clone();
-
-            v.sort();
-            assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-            v1.sort_by(|a, b| a.cmp(b));
-            assert!(v1.windows(2).all(|w| w[0] <= w[1]));
-
-            v1.sort_by(|a, b| b.cmp(a));
-            assert!(v1.windows(2).all(|w| w[0] >= w[1]));
+        for &modulus in &[5, 10, 100, 1000] {
+            for _ in 0..10 {
+                let orig: Vec<_> = rng.gen_iter::<i32>()
+                    .map(|x| x % modulus)
+                    .take(len)
+                    .collect();
+
+                // Sort in default order.
+                let mut v = orig.clone();
+                v.sort();
+                assert!(v.windows(2).all(|w| w[0] <= w[1]));
+
+                // Sort in ascending order.
+                let mut v = orig.clone();
+                v.sort_by(|a, b| a.cmp(b));
+                assert!(v.windows(2).all(|w| w[0] <= w[1]));
+
+                // Sort in descending order.
+                let mut v = orig.clone();
+                v.sort_by(|a, b| b.cmp(a));
+                assert!(v.windows(2).all(|w| w[0] >= w[1]));
+
+                // Sort with many pre-sorted runs.
+                let mut v = orig.clone();
+                v.sort();
+                v.reverse();
+                for _ in 0..5 {
+                    let a = rng.gen::<usize>() % len;
+                    let b = rng.gen::<usize>() % len;
+                    if a < b {
+                        v[a..b].reverse();
+                    } else {
+                        v.swap(a, b);
+                    }
+                }
+                v.sort();
+                assert!(v.windows(2).all(|w| w[0] <= w[1]));
+            }
         }
     }
 
diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index fdf453b39cf..17f1229c206 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -274,6 +274,11 @@ fn test_dedup_by() {
     vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
 
     assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
+
+    let mut vec = vec![("foo", 1), ("foo", 2), ("bar", 3), ("bar", 4), ("bar", 5)];
+    vec.dedup_by(|a, b| a.0 == b.0 && { b.1 += a.1; true });
+
+    assert_eq!(vec, [("foo", 3), ("bar", 12)]);
 }
 
 #[test]
diff --git a/src/liballoc/tests/vec_deque.rs b/src/liballoc/tests/vec_deque.rs
index a992351653d..f2935c05d4f 100644
--- a/src/liballoc/tests/vec_deque.rs
+++ b/src/liballoc/tests/vec_deque.rs
@@ -510,8 +510,7 @@ fn test_from_iter() {
     let u: Vec<_> = deq.iter().cloned().collect();
     assert_eq!(u, v);
 
-    // FIXME #27741: Remove `.skip(0)` when Range::step_by is fully removed
-    let seq = (0..).skip(0).step_by(2).take(256);
+    let seq = (0..).step_by(2).take(256);
     let deq: VecDeque<_> = seq.collect();
     for (i, &x) in deq.iter().enumerate() {
         assert_eq!(2 * i, x);