Allow watching workspaces at /tmp/some-dir (#4632)

* fix(watchman): allow watching workspaces at /tmp/some-dir

Fixes #4616

* Fix test of fileSystemWatcher.test.ts

---------

Co-authored-by: Qiming zhao <chemzqm@gmail.com>

src/__tests__/core/fileSystemWatcher.test.ts

@@ -246,8 +246,9 @@ describe('isValidWatchRoot()', () => {
   it('should check valid root', async () => {
     expect(isValidWatchRoot('/')).toBe(false)
     expect(isValidWatchRoot(os.homedir())).toBe(false)
-    expect(isValidWatchRoot('/tmp/a/b/c')).toBe(false)
     expect(isValidWatchRoot(os.tmpdir())).toBe(false)
+    expect(isValidWatchRoot('/tmp/a')).toBe(true)
+    expect(isValidWatchRoot('/tmp/a/b/c')).toBe(true)
   })
 })
 
@@ -307,7 +308,7 @@ describe('fileSystemWatcher', () => {
 
   it('should use relative pattern #3', async () => {
     let called = false
-    let root = path.join(os.tmpdir(), 'not_exists')
+    let root = path.join(process.cwd(), 'not_exists')
     let pattern = new RelativePattern(root, '**/*')
     let watcher = createWatcher(pattern, false, true, true)
     watcher.onDidCreate(() => {

src/core/watchman.ts

@@ -171,13 +171,11 @@ export default class Watchman {
 }
 
 /**
- * Exclude user's home, driver, tmpdir
+ * Exclude root, user's home, driver and tmpdir, but allow sub-directories under them.
  */
 export function isValidWatchRoot(root: string): boolean {
-  if (root == '/' || root == '/tmp' || root == '/private/tmp') return false
+  if (root == '/' || root == '/tmp' || root == '/private/tmp' || root == os.tmpdir()) return false
   if (isParentFolder(root, os.homedir(), true)) return false
   if (path.parse(root).base == root) return false
-  if (root.startsWith('/tmp/') || root.startsWith('/private/tmp/')) return false
-  if (isParentFolder(os.tmpdir(), root, true)) return false
   return true
 }