fix clippy::manual_map in tests

Author: hellow554

tests/test_core.rs

@@ -180,15 +180,10 @@ fn batching() {
     let ys = [(0, 1), (2, 1)];
 
     // An iterator that gathers elements up in pairs
-    let pit = xs.iter().cloned().batching(|it| {
-               match it.next() {
-                   None => None,
-                   Some(x) => match it.next() {
-                       None => None,
-                       Some(y) => Some((x, y)),
-                   }
-               }
-           });
+    let pit = xs
+        .iter()
+        .cloned()
+        .batching(|it| it.next().and_then(|x| it.next().map(|y| (x, y))));
     it::assert_equal(pit, ys.iter().cloned());
 }