More systemic test for k_smallest

Author: ejmount

tests/test_std.rs

@@ -434,29 +434,34 @@ qc::quickcheck! {
         let num_elements = min(k, m as _);
 
         // Compute the top and bottom k in various combinations
-        let smallest_by_smallest : Vec<_> = v.iter().cloned().k_smallest(k).collect();
-        let smallest_by_largest : Vec<_> = v.iter().cloned().k_largest_by_key(k, |x| -x).collect();
+        let smallest = v.iter().cloned().k_smallest(k);
+        let smallest_by = v.iter().cloned().k_smallest_by(k, Ord::cmp);
+        let smallest_by_key = v.iter().cloned().k_smallest_by_key(k, |&x| x);
 
-        let largest_by_smallest : Vec<_> = v.iter().cloned().k_smallest_by(k, |a,b| b.cmp(a)).collect();
-        let largest_by_largest : Vec<_> = v.iter().cloned().k_largest_by(k, Ord::cmp).collect();
+        let largest = v.iter().cloned().k_largest(k);
+        let largest_by = v.iter().cloned().k_largest_by(k, Ord::cmp);
+        let largest_by_key = v.iter().cloned().k_largest_by_key(k, |&x| x);
 
         // Check the variations produce the same answers and that they're right
-        assert_eq!(
-            smallest_by_smallest,
-            smallest_by_largest
-        );
-        assert_eq!(
-            largest_by_smallest,
-            largest_by_largest
-        );
-        assert_eq!(
-            sorted[..num_elements],
-            smallest_by_smallest[..], 
-        );
-        it::assert_equal(
-            sorted[sorted.len()-num_elements..].iter().rev(),
-            largest_by_smallest[..].iter()
-        );
+        for (a,b,c,d) in izip!(
+            sorted[..num_elements].iter().cloned(), 
+            smallest, 
+            smallest_by, 
+            smallest_by_key) {
+            assert_eq!(a,b);
+            assert_eq!(a,c);
+            assert_eq!(a,d);
+        }
+
+        for (a,b,c,d) in izip!(
+            sorted[sorted.len()-num_elements..].iter().rev().cloned(), 
+            largest, 
+            largest_by, 
+            largest_by_key) {
+            assert_eq!(a,b);
+            assert_eq!(a,c);
+            assert_eq!(a,d);
+        }
     }
 }