Fix race condition between opening new files and restoring window state

spec/atom-environment-spec.js

@@ -1,5 +1,6 @@
 const {it, fit, ffit, beforeEach, afterEach, conditionPromise} = require('./async-spec-helpers')
 const _ = require('underscore-plus')
+const fs = require('fs')
 const path = require('path')
 const temp = require('temp').track()
 const AtomEnvironment = require('../src/atom-environment')
@@ -471,15 +472,28 @@ describe('AtomEnvironment', () => {
         await atom.workspace.open()
       })
 
-      it('automatically restores the saved state into the current environment', () => {
-        const state = {}
-        spyOn(atom.workspace, 'open')
-        spyOn(atom, 'restoreStateIntoThisEnvironment')
-
-        atom.attemptRestoreProjectStateForPaths(state, [__dirname], [__filename])
-        expect(atom.restoreStateIntoThisEnvironment).toHaveBeenCalledWith(state)
-        expect(atom.workspace.open.callCount).toBe(1)
-        expect(atom.workspace.open).toHaveBeenCalledWith(__filename)
+      it('automatically restores the saved state into the current environment', async () => {
+        const projectPath = temp.mkdirSync()
+        const filePath1 = path.join(projectPath, 'file-1')
+        const filePath2 = path.join(projectPath, 'file-2')
+        const filePath3 = path.join(projectPath, 'file-3')
+        fs.writeFileSync(filePath1, 'abc')
+        fs.writeFileSync(filePath2, 'def')
+        fs.writeFileSync(filePath3, 'ghi')
+
+        const env1 = new AtomEnvironment({applicationDelegate: atom.applicationDelegate})
+        env1.project.setPaths([projectPath])
+        await env1.workspace.open(filePath1)
+        await env1.workspace.open(filePath2)
+        await env1.workspace.open(filePath3)
+        const env1State = env1.serialize()
+        env1.destroy()
+
+        const env2 = new AtomEnvironment({applicationDelegate: atom.applicationDelegate})
+        await env2.attemptRestoreProjectStateForPaths(env1State, [projectPath], [filePath2])
+        const restoredURIs = env2.workspace.getPaneItems().map(p => p.getURI())
+        expect(restoredURIs).toEqual([filePath1, filePath2, filePath3])
+        env2.destroy()
       })
 
       describe('when a dock has a non-text editor', () => {

src/atom-environment.js

@@ -373,7 +373,7 @@ class AtomEnvironment {
     if (this.project) this.project.destroy()
     this.project = null
     this.commands.clear()
-    this.stylesElement.remove()
+    if (this.stylesElement) this.stylesElement.remove()
     this.config.unobserveUserConfig()
     this.autoUpdater.destroy()
     this.uriHandlerRegistry.destroy()
@@ -1121,7 +1121,7 @@ class AtomEnvironment {
     }
 
     if (windowIsUnused()) {
-      this.restoreStateIntoThisEnvironment(state)
+      await this.restoreStateIntoThisEnvironment(state)
       return Promise.all(filesToOpen.map(file => this.workspace.open(file)))
     } else {
       let resolveDiscardStatePromise = null