Unit test heapsort

2 files changed, 32 insertions, 13 deletions

diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs
index 4f3b775ceb2..d92c378160d 100644
--- a/src/libcoretest/lib.rs
+++ b/src/libcoretest/lib.rs
@@ -26,6 +26,7 @@
 #![feature(raw)]
 #![feature(sip_hash_13)]
 #![feature(slice_patterns)]
+#![feature(sort_internals)]
 #![feature(sort_unstable)]
 #![feature(step_by)]
 #![feature(test)]
diff --git a/src/libcoretest/slice.rs b/src/libcoretest/slice.rs
index b51bae4db22..89bd3be0851 100644
--- a/src/libcoretest/slice.rs
+++ b/src/libcoretest/slice.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use core::slice::heapsort;
 use core::result::Result::{Ok, Err};
 use rand::{Rng, XorShiftRng};
 
@@ -226,26 +227,43 @@ fn get_unchecked_mut_range() {
 #[test]
 fn sort_unstable() {
     let mut v = [0; 600];
-    let mut v1 = [0; 600];
+    let mut tmp = [0; 600];
     let mut rng = XorShiftRng::new_unseeded();
 
     for len in (2..25).chain(500..510) {
-        for &modulus in &[10, 1000] {
+        let v = &mut v[0..len];
+        let tmp = &mut tmp[0..len];
+
+        for &modulus in &[5, 10, 100, 1000] {
             for _ in 0..100 {
                 for i in 0..len {
-                    let num = rng.gen::<i32>() % modulus;
-                    v[i] = num;
-                    v1[i] = num;
+                    v[i] = rng.gen::<i32>() % modulus;
                 }
 
-                v.sort_unstable();
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-                v1.sort_unstable_by(|a, b| a.cmp(b));
-                assert!(v1.windows(2).all(|w| w[0] <= w[1]));
-
-                v1.sort_unstable_by(|a, b| b.cmp(a));
-                assert!(v1.windows(2).all(|w| w[0] >= w[1]));
+                // Sort in default order.
+                tmp.copy_from_slice(v);
+                tmp.sort_unstable();
+                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
+
+                // Sort in ascending order.
+                tmp.copy_from_slice(v);
+                tmp.sort_unstable_by(|a, b| a.cmp(b));
+                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
+
+                // Sort in descending order.
+                tmp.copy_from_slice(v);
+                tmp.sort_unstable_by(|a, b| b.cmp(a));
+                assert!(tmp.windows(2).all(|w| w[0] >= w[1]));
+
+                // Test heapsort using `<` operator.
+                tmp.copy_from_slice(v);
+                heapsort(tmp, |a, b| a < b);
+                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
+
+                // Test heapsort using `>` operator.
+                tmp.copy_from_slice(v);
+                heapsort(tmp, |a, b| a > b);
+                assert!(tmp.windows(2).all(|w| w[0] >= w[1]));
             }
         }
     }