fix reroot bug caused by failure to return after adding new root to tree

tree/suite_test.go

@@ -59,6 +59,9 @@ func (c *testnode) SetParent(parent Node[*testnode, int]) {
 	c.parent = parent
 }
 
+func (c *testnode) UpdateNode(node Node[*testnode, int]) {
+}
+
 type TreeTestSuite struct {
 	suite.Suite
 }

tree/tree.go

@@ -70,6 +70,8 @@ func (t *Tree[T, id]) Insert(node Node[T, id]) error {
 		if err != nil {
 			if t.root.GetParentID() == node.GetID() { // parent does not exist but incoming node is parent of root
 				t.reroot(node)
+				t.nodeIndex.insert(node)
+				return nil
 			} else { // parent does not exist, do not add
 				return ParentNotFound
 			}

tree/treeops_test.go

@@ -0,0 +1,71 @@
+package tree
+
+func (tts *TreeTestSuite) TestNoParent() {
+	st, err := NewTree[*testnode, int]()
+	tts.Require().NoError(err, "Failed to initialize tree for testing")
+
+	nodes := []Node[*testnode, int]{
+		&testnode{id: 0, parentID: 0, name: "node0"},
+		&testnode{id: 1, parentID: 0, name: "node1"},
+		&testnode{id: 2, parentID: 0, name: "node2"},
+		&testnode{id: 3, parentID: 1, name: "node3"},
+		&testnode{id: 4, parentID: 1, name: "node4"},
+		&testnode{id: 5, parentID: 4, name: "node5"},
+		&testnode{id: 6, parentID: 5, name: "node6"},
+		&testnode{id: 7, parentID: 2, name: "node7"},
+		&testnode{id: 8, parentID: 2, name: "node8"},
+		&testnode{id: 9, parentID: 3, name: "node9"},
+		&testnode{id: 10, parentID: 3, name: "node10"},
+		&testnode{id: 11, parentID: 10, name: "node11"},
+		&testnode{id: 13, parentID: 12, name: "node13"},
+	}
+
+	for _, node := range nodes {
+		err := st.Insert(node)
+		if node.GetID() == 13 {
+			tts.Require().Error(err, "Node without parent should trigger error")
+			continue
+		}
+		tts.Require().NoError(err, "Failed to insert node into tree")
+	}
+}
+
+func (tts *TreeTestSuite) TestReroot() {
+	st, err := NewTree[*testnode, int]()
+	tts.Require().NoError(err, "Failed to initialize tree for testing")
+
+	nodes := []Node[*testnode, int]{
+		&testnode{id: 0, parentID: 12, name: "node0"},
+		&testnode{id: 1, parentID: 0, name: "node1"},
+		&testnode{id: 2, parentID: 0, name: "node2"},
+		&testnode{id: 3, parentID: 1, name: "node3"},
+		&testnode{id: 4, parentID: 1, name: "node4"},
+		&testnode{id: 5, parentID: 4, name: "node5"},
+		&testnode{id: 6, parentID: 5, name: "node6"},
+		&testnode{id: 7, parentID: 2, name: "node7"},
+		&testnode{id: 8, parentID: 2, name: "node8"},
+		&testnode{id: 9, parentID: 3, name: "node9"},
+		&testnode{id: 10, parentID: 3, name: "node10"},
+		&testnode{id: 11, parentID: 10, name: "node11"},
+		&testnode{id: 12, parentID: 27, name: "node13"},
+	}
+
+	for _, node := range nodes {
+		err := st.Insert(node)
+		tts.Require().NoError(err, "Failed to insert node into tree")
+	}
+
+	// start from root node (id: 0) without limit depth
+	c, err := st.Traverse(TraverseBreadthFirst, st.Root().GetID(), 0)
+	tts.Require().NoError(err, "Failed to traverse tree")
+
+	// Grab the resulting BFS output
+	var results []int
+	for node := range c {
+		results = append(results, node.GetID())
+	}
+
+	// Expected result should include all nodes in the tree
+	bfsExpectedOrder := []int{12, 0, 1, 2, 3, 4, 7, 8, 9, 10, 5, 11, 6}
+	tts.Equal(bfsExpectedOrder, results, "BFS traversal did not match expected order")
+}