Added test that CircularTupleWindows clone works correctly.

tests/tuples.rs

@@ -61,6 +61,30 @@ fn tuple_windows() {
     assert_eq!(None, iter.next());
 }
 
+#[test]
+fn circular_tuple_windows() {
+    let v = [1, 2, 3, 4, 5];
+
+    let mut iter = v.iter().cloned().circular_tuple_windows();
+    assert_eq!(Some((1,)), iter.next());
+    assert_eq!(Some((2,)), iter.next());
+    assert_eq!(Some((3,)), iter.next());
+
+    let mut iter = v.iter().cloned().circular_tuple_windows();
+    assert_eq!(Some((1, 2, 3, 4)), iter.next());
+    assert_eq!(Some((2, 3, 4, 5)), iter.next());
+    // Testing impl Clone for CircularTupleWindows
+    let mut iter2 = iter.clone();
+    assert_eq!(Some((3, 4, 5, 1)), iter.next());
+    assert_eq!(Some((3, 4, 5, 1)), iter2.next());
+    assert_eq!(Some((4, 5, 1, 2)), iter.next());
+    assert_eq!(Some((4, 5, 1, 2)), iter2.next());
+    assert_eq!(Some((5, 1, 2, 3)), iter.next());
+    assert_eq!(Some((5, 1, 2, 3)), iter2.next());
+    assert_eq!(None, iter.next());
+    assert_eq!(None, iter2.next());
+}
+
 #[test]
 fn next_tuple() {
     let v = [1, 2, 3, 4, 5];