Original URL: https://www.guru99.com/handling-ajax-call-selenium-webdriver.html

Handling AJAX Call in Selenium Webdriver

Ajax is a technique used for creating fast and dynamic web pages. This technique is asynchronous and uses a combination of Javascript and XML .

It will updates the part/s of a web page without reloading the whole page.

Some of the famous applications that uses AJAX technique are Gmail, Google Maps, Facebook, Youtube, etc.

In this tutorial, you will learn-

• What is Ajax
• How to handle Ajax call Using Selenium Webdriver
• Challenges in Handling Ajax Call in Selenium Webdriver

What is Ajax

AJAX stands for Asynchronous JavaScript & XML, and it allows the Web page to retrieve small amounts of data from the server without reloading the entire page.

For example, when you click on submit button,JavaScriptwill make a request to the server, interpret the result and update the current screen without reloading the webpage.

• An Ajax call is an asynchronous request initiated by the browser that does not directly result in a page transition. It means, if you fire an Ajax request, the user can still work on the application while the request is waiting for a response.
• AJAX sends HTTP requests from the client to server and then process the server‘s response, without reloading the entire page. So when you make an AJAX call, you are not pretty sure about the time taken by the server to send you a response.

From a tester‘s point of view, if you are checking the content or the element to be displayed , you need to wait till you get the response. During AJAX call the data is stored in XML format and retrieved from the server.

How to handle Ajax call Using Selenium Webdriver

The biggest challenge in handling Ajax call is knowing the loading time for the web page. Since the loading of the web page will last only for a fraction of seconds, it is difficult for the tester to test such application through automation tool. For that, Selenium Webdriver has to use the wait method on this Ajax Call.

So by executing this wait command, selenium will suspend the execution of currentTest Caseand wait for the expected or new value. When the new value or field appears, the suspended test cases will get executed by Selenium Webdriver.

Following are the wait methods that Selenium Webdriver can use

1. Thread.Sleep()

• Thread.Sleep () is not a wise choice as it suspends the current thread for the specified amount of time.
• In AJAX, you can never be sure about the exact wait time. So, your test will fail if the element won‘t show up within the wait time. Moreover, it increases the overhead because calling Thread.sleep(t) makes the current thread to be moved from the running queue to the waiting queue.
• After the time ‘t‘ reached, the current thread will move from the waiting queue to the ready queue, and then it takes some time to be picked by the CPU and be running.

1. Implicit Wait()

• This method tells webdriver to wait if the element is not available immediately, but this wait will be in place for the entire time the browser is open. So any search for the elements on the page could take the time the implicit wait is set for.

1. Explicit Wait()

• Explicit wait is used to freeze the test execution till the time a particular condition is met or maximum time lapses.

1. WebdriverWait

• It can be used for any conditions. This can be achieved with WebDriverWait in combination with ExpectedCondition
• The best way to wait for an element dynamically is checking for the condition every second and continuing to the next command in the script as soon as the condition is met.

But the problem with all these waits is, you have to mention the time out unit. What if the element is still not present within the time? So there is one more wait called Fluent wait.

1. Fluent Wait

• This is an implementation of the Wait interface having its timeout and polling interval. Each FluentWait instance determines the maximum amount of time to wait for a condition, as well as the frequency with which to check the condition.

Challenges in Handling Ajax Call in Selenium Webdriver

• Using "pause" command for handling Ajax call is not completely reliable. Long pause time makes the test unacceptably slow and increases theTestingtime. Instead, "waitforcondition" will be more helpful in testing Ajax applications.
• It is difficult to assess the risk associated with particular Ajax applications
• Given full freedom to developers to modify Ajax application makes the testing process challenging
• Creating automated test request may be difficult for testing tools as such AJAX application often use different encoding or serialization technique to submit POST data.

An Example for Ajax HANDLING

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.Assert;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class Ajaxdemo {

	private String URL = "http://demo.guru99.com/test/ajax.html";

	WebDriver driver;
	WebDriverWait wait;

	@BeforeClass
	public void setUp() {
		System.setProperty("webdriver.chrome.driver",".\\chromedriver.exe");
		//create chrome instance
		driver = new ChromeDriver();
		driver.manage().window().maximize();
		driver.navigate().to(URL);
	}

	@Test
	public void test_AjaxExample() {

		By container = By.cssSelector(".container");
		wait = new WebDriverWait(driver, 5);
		wait.until(ExpectedConditions.presenceOfElementLocated(container));

		//Get the text before performing an ajax call
		WebElement noTextElement = driver.findElement(By.className("radiobutton"));
		String textBefore = noTextElement.getText().trim();

		//Click on the radio button
		driver.findElement(By.id("yes")).click();

		//Click on Check Button
		driver.findElement(By.id("buttoncheck")).click();

		/*Get the text after ajax call*/
		WebElement TextElement = driver.findElement(By.className("radiobutton"));
		wait.until(ExpectedConditions.visibilityOf(TextElement));
		String textAfter = TextElement.getText().trim();

		/*Verify both texts before ajax call and after ajax call text.*/
		Assert.assertNotEquals(textBefore, textAfter);
		System.out.println("Ajax Call Performed");

		String expectedText = "Radio button is checked and it‘s value is Yes";

		/*Verify expected text with text updated after ajax call*/
		Assert.assertEquals(textAfter, expectedText);
		driver.close();
	}

}

Summary:

• AJAX allows the Web page to retrieve small amounts of data from the server without reloading the entire page.
• To test Ajax application, different wait methods should be applied
  • ThreadSleep
  • Implicit Wait
  • Explicit Wait
  • WebdriverWait
  • Fluent Wait
• Creating automated test request may be difficult for testing tools as such AJAX application often use different encoding or serialization technique to submit POST data.

原文地址：https://www.cnblogs.com/alicegu2009/p/9098699.html