Use a private utility function to wait for all native watchers to stop

src/atom-environment.coffee

@@ -46,7 +46,7 @@ TextBuffer = require 'text-buffer'
 Gutter = require './gutter'
 TextEditorRegistry = require './text-editor-registry'
 AutoUpdateManager = require './auto-update-manager'
-FileSystemManager = require './filesystem-manager'
+FileSystemManager = require('./filesystem-manager').default
 
 # Essential: Atom global for dealing with packages, themes, menus, and the window.
 #

src/filesystem-manager.js

@@ -222,3 +222,11 @@ export default class FileSystemManager {
     return watcher
   }
 }
+
+// Private: Return a Promise that resolves when all {NativeWatcher} instances associated with a FileSystemManager
+// have stopped listening. This is useful for `afterEach()` blocks in unit tests.
+export function stopAllWatchers (manager) {
+  return Promise.all(
+    Array.from(manager.liveWatchers, watcher => watcher.stop())
+  )
+}