自动化测试析疑——WebDriver启动时白屏挂起问题解决方法

WebDriver启动的时候很容易无限挂起，直到外围框架设定的超时时间达到而退出运行，给测试运行带来很大的困扰。而实际上WebDriver有一组timeout的设置方法，启动时的挂起属于页面加载的范畴，所以可以考虑用timeouts().pageLoadTimeout()来重新启动一个有效的实例来执行测试。

　　Java代码：

* Description: catch page load timeout Exception and restart a new session.
* 内容描述：通过页面跳转是否超时来测试WebDriver启动时是否发生挂死异常。
*
* @param driver RemoteWebDriver object.
* @param browser the browser mode.
* @param testUrl the url used to navigate by the driver.get method.
* @throws Exception
*/
private boolean hasLoadPageSucceeded(RemoteWebDriver driver, String browser, String testUrl) throws Exception {
try {
driver.manage().timeouts().pageLoadTimeout(5, TimeUnit.SECONDS);
driver.get(testUrl);
return true;
} catch (TimeoutException te) {
LOG.error("******************本次启动WebDriver异常挂起******************");
setBuildEnvChoice(browser);
driverObjectInitalize();
return false;
}
}
/**
* Description: catch page load timeout Exception and restart a new session.
* 内容描述：循环一定次数测试WebDriver启动是否挂死。
*
* @param driver RemoteWebDriver object.
* @param browser the browser mode.
* @param testUrl the url used to navigate by the driver.get method.
* @param repeatTimes retry times.
* @throws Exception
*/
private void driverStatusTest(RemoteWebDriver driver, String browser, String testUrl, int repeatTimes) throws Exception {
int index = 0;
boolean suspended = true;
while (index < repeatTimes && suspended){
suspended = !hasLoadPageSucceeded(driver, browser, testUrl);
index ++;
}
if (index == repeatTimes && suspended){
throw new RuntimeException("can not start webdriver successfully, it's suspended!");
}
}
/**
* Description: start webdirver after capability settings completed.
* 内容描述：在做好配置之后创建WebDriver实例。
*
* @throws Exception
*/
private String driverObjectInitalize() throws Exception{
if (USE_DRIVERSERVER){//是否使用IEDirverServer
driver = new RemoteWebDriver(service.getUrl(), capability);
return service.getUrl().toString();
}else{
URL url = new URL("http://localhost:" + server.getPort() + "/wd/hub");
driver = new RemoteWebDriver(url, capability);
return "http://localhost:" + server.getPort() + "/wd/hub";
}
}
/**
* Description: start webdirver
* 内容描述：启动WebDriver实例。
*
* @param browser the browser mode
* @throws RuntimeException
*/
protected void startWebDriver(String browser) {
try {
setBrowserMode(browser);
String url = driverObjectInitalize();//about:blank is useless on some machines.
driverStatusTest(driver, browser, url, 2);
driver.manage().timeouts().implicitlyWait(maxWaitfor, TimeUnit.SECONDS);
driver.manage().timeouts().setScriptTimeout(maxWaitfor, TimeUnit.SECONDS);
driver.manage().timeouts().pageLoadTimeout(maxLoadTime, TimeUnit.SECONDS);
} catch (Exception e) {
LOG.error(e);
throw new RuntimeException(e);
}
}
/**
* Description: set browser mode on local machines: do not close browsers already opened.
* 内容描述：选择在本机执行，有人工干预，无需杀掉浏览器进程。
*
* @throws Exception
*/
private void setBrowserMode(String browser) throws Exception{
if (browser.toLowerCase().contains("ie") || browser.toLowerCase().contains("internetexplorer")) {
capability = DesiredCapabilities.internetExplorer();
} else if (browser.toLowerCase().contains("ff") || browser.toLowerCase().contains("firefox")) {
capability = DesiredCapabilities.firefox();
} else if (browser.toLowerCase().contains("chrome")) {
capability = DesiredCapabilities.chrome();
} else if (browser.toLowerCase().contains("safari")) {
capability = DesiredCapabilities.safari();
} else if (browser.toLowerCase().contains("opera")) {
capability = DesiredCapabilities.opera();
} else if (browser.toLowerCase().contains("htmlunit")) {
capability = DesiredCapabilities.htmlUnit();
} else {
throw new IllegalArgumentException("you are using wrong mode of browser paltform!");
}
}

上面的文档给出的解决方案只是能够部分地解决工具问题，但有时候这种hang死会发生在timeouts().pageLoadTimeout()发生作用之前。也就是说，这需要更为彻底的方法去解决这个问题，我想到最简单的方式是用独立的守护线程去看守，具体代码如下：

[html] view plaincopyprint?private final int DRIVER_STATUS_TEST_TIMES = 2;
private final int DRIVER_START_TIMEOUT = 30000;
/**
* Description: start webdirver
* 内容描述：启动WebDriver实例。
*
* @param browserMode the browser mode
*/
private void startWebDriver(String browserMode){
try {
setBuildEnvChoice(browserMode);
initalizeWebDriver(DRIVER_START_TIMEOUT);
//the address "about:blank" is sometimes useless.
ensureWebDriverStatus(browserMode, getServerAddress(), DRIVER_STATUS_TEST_TIMES);
setPageLoadTimeout(maxLoadTime);
setElementLocateTimeout(maxWaitfor);
setScriptingTimeout(maxWaitfor);
actionDriver = new Actions(driver);
ASSERT = new StarNewAssertion(driver, LOG_ABS, className, logger, devidor);
pass("webdriver new instance created");
} catch (Exception e) {
LOG.error(e);
throw new RuntimeException(e);
}
}
/**
* Description: start webdirver using browser iexplore
* 内容描述：默认选择IE模式创建WebDriver实例。
*/
protected void startWebDriver() {
startWebDriver("ie");
}
/**
* Description: start webdirver after capabilities settings completed.
* 内容描述：在做好配置之后创建WebDriver实例。
*/
private void initalizeWebDriver() {
WebDriverListener listener = new WebDriverListener(LOG_ABS, className, logger, devidor);
if (USE_DRIVERSERVER) {// 是否使用IEDirverServer
driver = new EventFiringWebDriver(new RemoteWebDriver(service.getUrl(), capabilities)).register(listener);
} else {
try {
URL url = new URL("http://localhost:" + server.getPort() + "/wd/hub");
driver = new EventFiringWebDriver(new RemoteWebDriver(url, capabilities)).register(listener);
} catch (MalformedURLException e) {
throw new RuntimeException("illegal url!");
}
}
}
/**
* Description: start and see if webdirver start successfully.
* 内容描述：创建并且判断WebDriver实例是否启动成功。
*
* @param timeout timeout for start webdriver.
* @param redoCount retry times for start webdriver.
* @throws Exception
*/
private void initalizeWebDriver(long timeout, int redoCount) throws Exception {
for (int i = 0; i < redoCount; i++) {
Thread thread_start = new Thread(new Runnable() {
public void run() {// 用一个独立的线程启动WebDriver
initalizeWebDriver();
}
});
thread_start.start();
waitFor(thread_start, timeout);//为启动WebDriver设定超时时间
if (!thread_start.isAlive()) {
return;
} else {
thread_start.interrupt();
consoleError("start Webdriver failed 【" + i + "】 times!");
}
if (thread_start.isAlive() && i == redoCount){// 如果最终没能启动成功则抛出错误
thread_start.interrupt();
throw new RuntimeException("can not start webdriver, check your platform configurations!");
}
}
}

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