11个基本的硒面试问题 *

要等待页面加载，可以使用显式等待. 显式等待停止，直到满足某些特定条件. Although Thread.Sleep() is a form of explicit wait where the thread stalls for a specific duration of time, it may not be the most reliable way to wait for a page to load.

例如，而不是使用这样的东西:

Thread.睡眠(30000);

… where the thread sleeps for 30 seconds (30,000 milliseconds), the following can be used:

WebDriverWait = new WebDriverWait(webDriver,30);
wait.直到(ExpectedConditions.visibilityOf (h1));

… where Selenium waits until the given element is visible on the page, 或在等待30秒后抛出TimeoutException.

Page Object Model in Selenium is a design pattern where web pages are represented using classes. Variables in the class can then be used to hold references to elements on the web page, 方法可以用来实现行为. This allows an elegant way of implementing test routines that are both readable and easier to maintain and extend in the future.

clickLoginButton ();
setCredentials (user_name user_password);
submitLoginForm ();

Page Factory is used to initialize every WebElement variable with a reference to a corresponding element on the actual web page using configured “locators”. Annotations, 例如@FindBy, 可以用来定义查找元素的策略吗, 连同识别他们的必要资料:

@FindBy(如何=.的名字,使用= "用户名")
私有WebElement user_name;

可以找到更多关于页面对象模型和页面工厂的信息 here.

In order to manipulate frame and its content you must switch to it first. This is similar to how you have to switch to a different page before you can interact with it:

driver.switchTo().框架(指数);

… where index 是坐标系的从零开始的索引吗. Switching the frame directs all further interactions through the driver towards the selected frame. The frame method also works with name, element ID and reference to already located elements.

要切换回默认帧，请使用 defaultContent 方法可采用:

driver.switchTo().defaultContent ();

• CSS选择器通常比XPath更容易阅读. Most front-end developers are more likely to be familiar with CSS selectors already.

• Support for CSS selectors is quite consistent across various modern web browsers, 而他们的XPath引擎却不是这样.

• CSS选择器比XPath工作得快.

出于各种原因, 比如上面列出的那些, Selenium “best practices” advise the use of CSS selectors over XPath.

直接子:

An immediate child in XPath is defined indicated using “/”, while on CSS, it is indicated using “>”. 例如，使用XPath:

//div/p

使用CSS:

div > p

后代:

To find paragraph elements that are descendent to any div element (i.e. the paragraph element appears in the subtree rooted at the div element), 我们可以在XPath中使用“//”, 只是一个空白的CSS:

//div//p

div p

它定义了一个变量 sample 类型为WebElement, and uses an XPath search to initialize it with a reference to an element that contains the text value “data”.

This can be done by simulating key presses on the focused element. 一种方法是在web驱动对象上执行“actions”:

新的行动(webDriver).sendKeys(“文本”).perform();

An alternative way is to switch to the active element first, and send keys to it directly:

webDriver.switchTo().activeElement ().sendKeys(“文本”);

无头的司机 are typically used in continuous integration (CI) setups. 无头的司机, 比如PhantomJS, 提供所有标准的web浏览器功能, 但是在命令行中运行. These drivers are based on command-line tools and don’t produce screen output, 使它们成为完全自动化设置的理想选择.

能够直观地调查测试失败, the developer needs to implement mechanisms to capture screenshots, 否则依赖于命令行输出.

Absolute XPaths, in terms of web pages, start with the root element:

html /头/身体/表/身体/ tr / th

另一方面，相对xpath通常以" // "开头:

/ /表/身体/ tr / th 

Even though both these XPaths probably refer to the same element on a certain web page, the former one is more likely to break with any change made to the page. For example, moving the table to inside of a div element will stop the absolute XPath from being able to locate the th element. On the other hand, the relative XPath will still continue to work.

A hybrid framework is a combination of keyword- and data-driven frameworks.

It is the exception thrown when the invoked element is no longer attached to the DOM for any reason.