javascript - Selenium WebDriverJS thenCatch 没有捕获 StaleElementException

Question

我正在运行 node.js 和 Selenium WebDriverJS。我的一项测试因以下错误而失败:

UnknownError: unknown error: Runtime.evaluate threw exception: Error: element is not attached to the page document

我知道这本质上是一个 StaleElementReferenceException，但我一直无法找到可靠的解决方法。我尝试了以下但没有成功:

1. 在找到并点击元素之前等待元素出现在页面上

   waitForElement: function (selector, timeout) {
       if (typeof(timeout) === 'undefined') { timeout = 3000; }
       driver.wait(function() {
           return driver.findElements(selector).then(function(list) {
               return list.length > 0;
           });
       }, timeout);
   }
   

2. 在找到并点击元素之前等待一段明确的时间(driver.sleep(1000))
3. 在点击元素之前多次查找元素(使用 .findElement())

4. 使用 promise 链捕获任何错误并尝试重新点击该元素

   driver.getTitle().then(function(title) {
       driver.findElement(webdriver.By.xpath(...)).click();
   }).thenCatch(function(e) {
       driver.findElement(webdriver.By.xpath(...)).click();
   });
   

5. 使用具有递归函数的 promise 链来不断尝试重新单击该元素

   var getStaleElement = function(selector, callback) {
       var element = driver.findElement(selector);
       callback(element);
   }).thenCatch(function(e) {
       getStaleElement(selector, callback);
   });
   
   var clickSelf = function(ele) { return ele.click() };
   
   driver.getTitle().then(function(title) {
       driver.findElement(webdriver.By.xpath(...)).click();
   }).thenCatch(function(e) {
       getStaleElement(webdriver.By.xpath(...), clickSelf);
   });
   

6. 方法 4 和 5 使用 .then() 的 errback 参数代替 .thenCatch()
7. 上述的组合

似乎 Selenium 无法捕获此特定错误。我使用 print 语句来确认 .thenCatch() 捕获了其他错误，例如 NoSuchElementError。是否有一种解决方法可以让我处理陈旧的元素？

Answer 1

我遇到了类似的问题，所以我做了下面的解决方法，你可以试一试......

/*
 * params.config - {
 *           opposite - {Boolean} - if true, will wait till negative result is reached/ error is thrown.
 *           maxWaitTime - {Number} - if this time exceeds, just throw an error and leave.
 *           waitTime - {Number} - wait time between two checks.
 *           expectValue - {Boolean} - where you just want it to run without error, or it should expect a value
 *           expectedValue - {Object} - object value it should or should not match.
 *         }
 *  params.fn - a function that returns a promise that we want to keep checking till desire value is reached
 */
function waiter(fn, config){
    config = config || {};
    var deffered = Driver.promise.defer(),  
        wt = config.waitTime || 100,
        mwt = config.maxWaitTime || 3000,
        timeoutReached = false,
        pCall = function(){
                        fn().then(pThen, pCatch);
                    },
        pThen = function(data){
                    if(timeoutReached)  return;
                    if(config.expectValue){
                        if(config.opposite){                        
                            if(data == config.expectedValue){
                                setTimeout(pCall, wt);
                            }else{
                                clearTimeout(vTimeout);
                                deffered.fulfill(true);
                            }
                        }else{
                            if(data == config.expectedValue){
                                clearTimeout(vTimeout);
                                deffered.fulfill(true);
                            }else{
                                setTimeout(pCall, wt);
                            }
                        }
                    }else{
                        deffered.fulfill(true);
                    }
                },  
        pCatch = function(err){
                    if(timeoutReached)  return;
                    if(config.opposite){
                        deffered.fulfill(true);
                    }else{
                        setTimeout(pCall, wt);
                    }
                };  

    pCall();    

    var vTimeout = setTimeout(function(){
        timeoutReached = true;
        if(config.opposite){
            deffered.fulfill(true);         
        }else{
            deffered.reject(new Error('timed-out'));
        }
    }, mwt);
    return deffered.promise;
}

示例用法(针对您的情况):

var myPromise = function(){
    return driver.findElement(webdriver.By.xpath(...)).click();
};

//default use
waiter(myPromise).then(function(){
    console.log('finally...');
}).catch(fucntion(err){
    console.log('not working: ', err);
});

// with custom timeout after 10 seconds
waiter(myPromise, {maxWaitTime: 10000}).then(function(){
    console.log('finally...');
}).catch(fucntion(err){
    console.log('not working: ', err);
});