Implement pop_back for kv

sewup/src/kv/bucket.rs

@@ -261,8 +261,18 @@ impl<'a, K: Key + PartialEq, V: Clone + Value> Bucket<K, V> {
     }
 
     /// Pop the last item
-    pub fn pop_back(&self) -> Option<Item<K, V>> {
-        None
+    pub fn pop_back(&mut self) -> Option<Item<K, V>> {
+        let mut prev_pair: Option<(K, V)> = None;
+        let mut iter = self.iter();
+        while let Some(pair) = iter.next() {
+            prev_pair = Some(pair);
+        }
+        if let Some((key, value)) = prev_pair {
+            self.remove(key.clone());
+            Some((key, value))
+        } else {
+            None
+        }
     }
 
     /// Pop the first item

sewup/src/kv/tests.rs

@@ -38,3 +38,21 @@ fn test_pop_for_bucket() {
     assert_eq!(bucket.get(2).unwrap(), None);
     assert_eq!(bucket.get(3).unwrap(), Some(3));
 }
+
+#[cfg(feature = "default")]
+#[test]
+fn test_pop_back_for_bucket() {
+    let mut bucket = Bucket {
+        name: "test_bucket".into(),
+        raw_bucket: (vec![], vec![]),
+        phantom_k: PhantomData::<usize>,
+        phantom_v: PhantomData::<usize>,
+    };
+    bucket.set(1, 1);
+    bucket.set(2, 2);
+    assert_eq!(bucket.get(1).unwrap(), Some(1));
+    let last = bucket.pop_back();
+    assert_eq!(last, Some((2, 2)));
+    assert_eq!(bucket.get(1).unwrap(), Some(1));
+    assert_eq!(bucket.get(2).unwrap(), None);
+}