我得到一个错误，它是“unhandledpromiserejectionwarning：nosuchsessionerror：没有这样的会话”

Question

我试图用Selenium×Node.js实现自动化测试，但它在调查阶段被阻止了...

• Mac OS10.12.6
• 节点8.11.1
• Selenium Server 3.12.0
• Selenium WebDriver 4.0.0
• ChromeDriver 2.38

$ npm install selenium-webdriver

3.安装selenium-server

通过自制安装

$ brew install selenium-server-standalone

4.安装ChromeDriver

$ mv /Users/username/Downloads/chromedriver ./
$ ls -la
total 31920 
drwxr-xr-x 7 username staff 238 5 24 17:42 . 
drwxr-xr-x+ 55 username staff 1870 5 24 17:42 .. 
-rwxr-xr-x@ 1 username staff 11917200 4 20 16:39 chromedriver 
drwxr-xr-x 41 username staff 1394 5 24 16:45 node_modules 
-rw-r--r-- 1 username staff 9367 5 24 16:45 package-lock.json

$selenium-server-port 4444&[1]33415 c02sy1xfgtfj:Selenium用户名$18:04:14.512信息[gridlauncherv3.launn]-Selenium构建信息：版本：“3.11.0”，修订：“e59cfb3”18:04:14.513信息[gridlauncherv3$1.launn]-在端口4444 2018-05-24 18:04:14.624:INFO::main:Logging initialized@441ms到org.seleniumhq.jetty9.util.log.stderrlog 18:04:14.882 ver.boot]-欢迎使用Selenium for Workgroups....18:04:14.882信息[SeleniumServer.boot]-Selenium服务器已启动并在端口4444上运行

编写测试代码作为示例

$ vim sample.js

// Initialization of WebDriver
const webdriver = require('selenium-webdriver');
// Browser html" target="_blank">selection
const browser = new webdriver.Builder().forBrowser('chrome').build();

// Get page title
browser.get('http://example.selenium.jp/reserveApp/').then(()=>{
    browser.getTitle().then(title => console.log('Page title:',title))
});

// Exit the browser
browser.close();
browser.quit();

当您执行上述代码时，...

$ node sample.js 
(node:13216) UnhandledPromiseRejectionWarning: NoSuchSessionError: no such session
  (Driver info: chromedriver=2.38.552518 (183d19265345f54ce39cbb94cf81ba5f15905011),platform=Mac OS X 10.12.6 x86_64)
    at Object.checkLegacyResponse (/Users/ko-kamenashi/selenium/node_modules/selenium-webdriver/lib/error.js:585:15)
    at parseHttpResponse (/Users/ko-kamenashi/selenium/node_modules/selenium-webdriver/lib/http.js:533:13)
at Executor.execute (/Users/ko-kamenashi/selenium/node_modules/selenium-webdriver/lib/http.js:468:26)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:188:7)
(node:13216) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:13216) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

我有错误。我该怎么办？你能帮我一把吗？谢谢你的阅读。

Answer 1

错误在这里：const browser=new webdriver.builder().forbrowser('chrome').build（）；

Best way: 
(async ()=> { 
await const browser = new webdriver.Builder().forBrowser('chrome').build();
)();