面试题与答案

XPath is also defined as XML Path. It is a language used to query XML documents. It is an important approach to locate elements in Selenium. XPath consists of a path expression along with some conditions. Here, we can easily write XPath script/query to locate any element in the webpage. It is developed to allow the navigation of XML documents. The key factors that it considered while navigating are selecting individual elements, attributes, or some other part of an XML document for specific processing. It also produces reliable locators. Some other points about XPath are as follows.

• XPath is a language used for locating nodes in XML documents.
• XPath can be used as a substitute when you don't have a suitable id or name attribute for the element you want to locate.
• XPath provides locating strategies like:
  • XPath Absolute
  • XPath Attributes

XPath Absolute:

• XPath Absolute enables users to mention the complete XPath location from the root HTML tag to the specific elements.
• Syntax: //html/body/tag1[index]/tag2[index]/.../tagN[index]
• Example: //html/body/div[2]/div/div[2]/div/div/div/fieldset/form/div[1]/input[1]

XPath Attributes:

• XPath Attributes is always recommended when you don't have a suitable id or name attribute for the element you want to locate.
• Syntax: //htmltag[@attribute1='value1' and @attribute2='value2']
• Example: //input[@id='passwd' and @placeholder='password']

"type" command is used to type keyboard key values into the text box of software web application. It can also be used for selecting values of combo box whereas "typeAndWait" command is used when your typing is completed and software web page start reloading. This command will wait for software application page to reload. If there is no page reload event on typing, you have to use a simple "type" command.

findElement(): It is used to find the first element within the current page using the given "locating mechanism". It returns a single WebElement.

findElements(): It uses the given "locating mechanism" to find all the elements within the current page. It returns a list of web elements.

Selenium Webdriver introduces the concept of waits for the AJAX-based application. There are two types of waits:

1. Implicit Wait
2. Explicit Wait

The main disadvantage of implicit wait is that it slows down test performance.

Another disadvantage of implicit wait is:

Suppose, you set the waiting limit to be 10 seconds, and the elements appear in the DOM in 11 seconds, your tests will be failed because you told it to wait a maximum of 10 seconds.

Selenium Grid facilitates you to distribute your tests on multiple machines and all of them at the same time. So, you can execute tests on Internet Explorer on Windows and Safari on Mac machine using the same text script. It reduces the time of test execution and provides quick feedback.

We have to create an instance of a driver of that particular browser.

Here, "WebDriver" is an interface, and we are creating a reference variable "driver" of type WebDriver, instantiated using "FireFoxDriver" class.

public class FirefoxBrowserLaunchDemo {  
  
 public static void main(String[] args) {  
  
  //Creating a driver object referencing WebDriver interface  
  WebDriver driver;  
  
  //Setting webdriver.gecko.driver property  
  System.setProperty("webdriver.gecko.driver", pathToGeckoDriver + "\\geckodriver.exe");  
  
  //Instantiating driver object and launching browser  
  driver = newFirefoxDriver();  
  
  //Using get() method to open a webpage  
  driver.get("http://javatpoint.com");  
  
  //Closing the browser  
  driver.quit();  
  
 }  
  
}  

public class ChromeBrowserLaunchDemo {  
  
  public static void main(String[] args) {  
  
    //Creating a driver object referencing WebDriver interface  
    WebDriver driver;  
  
    //Setting the webdriver.chrome.driver property to its executable's location  
    System.setProperty("webdriver.chrome.driver", "/lib/chromeDriver/chromedriver.exe");  
      
    //Instantiating driver object  
    driver = newChromeDriver();  
  
    //Using get() method to open a webpage  
    driver.get("http://javatpoint.com");  
  
    //Closing the browser  
    driver.quit();  
  
  }  
}  

public class IEBrowserLaunchDemo {  
  
  public static void main(String[] args) {  
  
    //Creating a driver object referencing WebDriver interface  
    WebDriver driver;  
  
    //Setting the webdriver.ie.driver property to its executable's location  
    System.setProperty("webdriver.ie.driver", "/lib/IEDriverServer/IEDriverServer.exe");  
      
    //Instantiating driver object  
    driver = newInternetExplorerDriver();  
  
    //Using get() method to open a webpage  
    driver.get("http://javatpoint.com");  
  
    //Closing the browser  
    driver.quit();  
  
  }  
  
}