Fix reparent methods to update parent for all siblings

Previously only first and last siblings had their parent updated,
leaving middle siblings with stale parent references.

Author: amirshukayev

src/lib.rs

@@ -843,9 +843,12 @@ impl<'a, T: 'a> NodeMut<'a, T> {
             }
         };
 
-        unsafe {
-            self.tree.node_mut(new_child_ids.0).parent = Some(self.id);
-            self.tree.node_mut(new_child_ids.1).parent = Some(self.id);
+        // Update parent for all siblings in the chain
+        let mut child_id = new_child_ids.0;
+        loop {
+            unsafe { self.tree.node_mut(child_id).parent = Some(self.id); }
+            if child_id == new_child_ids.1 { break; }
+            child_id = unsafe { self.tree.node_mut(child_id).next_sibling.unwrap() };
         }
 
         if self.node().children.is_none() {
@@ -882,9 +885,12 @@ impl<'a, T: 'a> NodeMut<'a, T> {
             }
         };
 
-        unsafe {
-            self.tree.node_mut(new_child_ids.0).parent = Some(self.id);
-            self.tree.node_mut(new_child_ids.1).parent = Some(self.id);
+        // Update parent for all siblings in the chain
+        let mut child_id = new_child_ids.0;
+        loop {
+            unsafe { self.tree.node_mut(child_id).parent = Some(self.id); }
+            if child_id == new_child_ids.1 { break; }
+            child_id = unsafe { self.tree.node_mut(child_id).next_sibling.unwrap() };
         }
 
         if self.node().children.is_none() {

tests/node_mut.rs

@@ -492,6 +492,70 @@ fn reparent_from_id_prepend() {
     assert_eq!(Some(d), f.prev_sibling());
 }
 
+#[test]
+fn reparent_from_id_append_multiple_siblings() {
+    // Test reparenting when source has 3+ children to ensure all siblings get proper parent update
+    let mut tree = tree! {
+        'a' => {
+            'b' => { 'x' },  // destination node
+            'c' => { 'd', 'e', 'f' },  // source node with 3 children
+        }
+    };
+
+    let c_id = tree.root().last_child().unwrap().id();
+    let b_id = tree.root().first_child().unwrap().id();
+
+    // Reparent children from 'c' to 'b'
+    tree.root_mut()
+        .first_child()
+        .unwrap()
+        .reparent_from_id_append(c_id);
+
+    let b = tree.get(b_id).unwrap();
+    let x = b.first_child().unwrap();  // original child of b
+    let d = x.next_sibling().unwrap();  // first reparented child
+    let e = d.next_sibling().unwrap();  // middle reparented child
+    let f = e.next_sibling().unwrap();  // last reparented child
+
+    // All children should now have 'b' as their parent
+    assert_eq!(Some(b), x.parent());
+    assert_eq!(Some(b), d.parent());
+    assert_eq!(Some(b), e.parent());
+    assert_eq!(Some(b), f.parent());
+}
+
+#[test]
+fn reparent_from_id_prepend_multiple_siblings() {
+    // Test reparenting when source has 3+ children to ensure all siblings get proper parent update
+    let mut tree = tree! {
+        'a' => {
+            'b' => { 'x' },  // destination node
+            'c' => { 'd', 'e', 'f' },  // source node with 3 children
+        }
+    };
+
+    let c_id = tree.root().last_child().unwrap().id();
+    let b_id = tree.root().first_child().unwrap().id();
+
+    // Reparent children from 'c' to 'b'
+    tree.root_mut()
+        .first_child()
+        .unwrap()
+        .reparent_from_id_prepend(c_id);
+
+    let b = tree.get(b_id).unwrap();
+    let d = b.first_child().unwrap();  // first reparented child
+    let e = d.next_sibling().unwrap(); // middle reparented child
+    let f = e.next_sibling().unwrap(); // last reparented child
+    let x = f.next_sibling().unwrap(); // original child of b
+
+    // All children should now have 'b' as their parent
+    assert_eq!(Some(b), d.parent());
+    assert_eq!(Some(b), e.parent());
+    assert_eq!(Some(b), f.parent());
+    assert_eq!(Some(b), x.parent());
+}
+
 #[test]
 fn into() {
     let mut tree = tree!('a');