test(tree): add tests for getTreePaths function

Author: honghuangdc

src/tree.test.ts

@@ -1,6 +1,11 @@
 import { describe, expect, it } from 'vitest';
 
-import { buildTree } from './tree';
+import { buildTree, getTreePaths } from './tree';
+
+type TestTreeNode = {
+  id: number;
+  children?: TestTreeNode[];
+};
 
 describe('tree utils', () => {
   it('builds a nested tree from flat nodes', () => {
@@ -18,4 +23,48 @@ describe('tree utils', () => {
     expect(tree[0].children?.[0].id).toBe(2);
     expect(tree[0].children?.[0].children?.[0].id).toBe(3);
   });
+
+  it('gets the path to a nested node', () => {
+    const nodes: TestTreeNode[] = [
+      {
+        id: 1,
+        children: [
+          {
+            id: 2,
+            children: [{ id: 3 }]
+          }
+        ]
+      }
+    ];
+
+    const paths = getTreePaths('id', 3, nodes);
+
+    expect(paths).toEqual([1, 2, 3]);
+  });
+
+  it('returns an empty array when the target node does not exist', () => {
+    const nodes: TestTreeNode[] = [
+      {
+        id: 1,
+        children: [{ id: 2 }]
+      }
+    ];
+
+    const paths = getTreePaths('id', 9, nodes);
+
+    expect(paths).toEqual([]);
+  });
+
+  it('supports falsy target values like 0', () => {
+    const nodes: TestTreeNode[] = [
+      {
+        id: 0,
+        children: [{ id: 1 }]
+      }
+    ];
+
+    const paths = getTreePaths('id', 0, nodes);
+
+    expect(paths).toEqual([0]);
+  });
 });

src/tree.ts

@@ -41,26 +41,22 @@ export const buildTree = <K extends string, P extends string, T extends BaseFlat
   return tree;
 };
 
-type BaseNode<K extends string, V extends string | number> = {
+type BaseNode<K extends string, V extends string | number = string | number> = {
   [key in K]: V;
 };
 
-type BaseTreeNode<K extends string, V extends string | number, T extends BaseNode<K, V>> = T & {
-  children?: Array<BaseTreeNode<K, V, T>>;
+type BaseTreeNode<K extends string, T extends BaseNode<K>> = T & {
+  children?: Array<BaseTreeNode<K, T>>;
 };
 
-export const getTreePaths = <K extends string, V extends string | number, T extends BaseNode<K, V>>(
+export const getTreePaths = <K extends string, T extends BaseNode<K>>(
   nodeKey: K,
-  target: V,
-  nodes: BaseTreeNode<K, V, T>[]
+  target: T[K],
+  nodes: BaseTreeNode<K, T>[]
 ) => {
-  const paths: V[] = [];
+  const paths: T[K][] = [];
 
-  if (!target) {
-    return paths;
-  }
-
-  function dfs(node: BaseTreeNode<K, V, T>, path: V[]): V[] | null {
+  function dfs(node: BaseTreeNode<K, T>, path: T[K][]): T[K][] | null {
     const currentPath = [...path, node[nodeKey]];
 
     // if find the target value, return the path