feat(tools): junction.mjs 跨平台目录链接创建/检测

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cocoscreator_projects/scripts/lib/junction.mjs

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+import { symlinkSync, lstatSync, existsSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { platform } from 'node:process';
+
+// Windows 用 junction（免管理员、仅限目录）；其它平台用 dir 符号链接
+const LINK_TYPE = platform === 'win32' ? 'junction' : 'dir';
+
+export function isLink(p) {
+  try {
+    return lstatSync(p).isSymbolicLink();
+  } catch {
+    return false;
+  }
+}
+
+// 在 linkPath 建一个指向 targetPath 的目录链接。
+// 返回 'created' | 'exists'；目标不存在或 linkPath 已被真实文件占用则抛错。
+export function ensureJunction(linkPath, targetPath) {
+  const target = resolve(targetPath); // junction 要求绝对目标
+  if (!existsSync(target)) {
+    throw new Error(`junction target 不存在: ${target}`);
+  }
+  if (isLink(linkPath)) return 'exists';
+  if (existsSync(linkPath)) {
+    throw new Error(`路径已存在且非链接，拒绝覆盖: ${linkPath}`);
+  }
+  symlinkSync(target, linkPath, LINK_TYPE);
+  return 'created';
+}

cocoscreator_projects/scripts/test/junction.test.mjs

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+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { join } from 'node:path';
+import { existsSync, readFileSync, writeFileSync } from 'node:fs';
+import { makeTempMonorepo, cleanup } from './helpers.mjs';
+import { ensureJunction, isLink } from '../lib/junction.mjs';
+
+test('ensureJunction 创建链接后可经链接读到真源文件', () => {
+  const mono = makeTempMonorepo();
+  try {
+    const link = join(mono.games, 'demo-framework');
+    const status = ensureJunction(link, mono.framework);
+    assert.equal(status, 'created');
+    assert.ok(isLink(link));
+    assert.equal(readFileSync(join(link, 'README.md'), 'utf8'), '# framework src\n');
+  } finally {
+    cleanup(mono.root);
+  }
+});
+
+test('ensureJunction 对已存在链接返回 exists 且不抛错', () => {
+  const mono = makeTempMonorepo();
+  try {
+    const link = join(mono.games, 'demo-framework');
+    ensureJunction(link, mono.framework);
+    assert.equal(ensureJunction(link, mono.framework), 'exists');
+  } finally {
+    cleanup(mono.root);
+  }
+});
+
+test('ensureJunction 目标不存在时抛错', () => {
+  const mono = makeTempMonorepo();
+  try {
+    assert.throws(() => ensureJunction(join(mono.games, 'x'), join(mono.root, 'no-such')), /target 不存在/);
+  } finally {
+    cleanup(mono.root);
+  }
+});
+
+test('ensureJunction 拒绝覆盖已存在的真实目录/文件', () => {
+  const mono = makeTempMonorepo();
+  try {
+    const link = join(mono.games, 'realfile');
+    writeFileSync(link, 'x');
+    assert.throws(() => ensureJunction(link, mono.framework), /非链接/);
+  } finally {
+    cleanup(mono.root);
+  }
+});