Change test to quickcheck

tests/quick.rs

@@ -1188,3 +1188,24 @@ quickcheck! {
         }
     }
 }
+
+quickcheck! {
+    #[test]
+    fn counts(nums: Vec<isize>) -> TestResult {
+        let counts = nums.iter().counts();
+        for (&item, &count) in counts.iter() {
+            if count <= 0 {
+                return TestResult::failed();
+            }
+            if count != nums.iter().filter(|&x| x == item).count() {
+                return TestResult::failed();
+            }
+        }
+        for item in nums.iter() {
+            if !counts.contains_key(item) {
+                return TestResult::failed();
+            }
+        }
+        TestResult::passed()
+    }
+}

tests/test_std.rs

@@ -913,16 +913,3 @@ fn tree_fold1() {
         assert_eq!(actual, expected);
     }
 }
-
-#[test]
-fn counts() {
-    let a: [usize; 0] = [];
-    assert_eq!(0, a.iter().counts().len());
-    let b = [1, 1, 1, 2, 2, 3];
-    let b_counts = b.iter().counts();
-    assert_eq!(3, b_counts.len());
-    assert_eq!(Some(&3), b_counts.get(&1));
-    assert_eq!(Some(&2), b_counts.get(&2));
-    assert_eq!(Some(&1), b_counts.get(&3));
-    assert_eq!(None, b_counts.get(&4));
-}