What is TestNG listener and How to implement in Selenium

What is TestNG Listener

In last post, we have discussed WebDriver Listener and hope you understood the actual concept of listeners, if not I will strongly recommend you that please go through WebDriver Listener  also.

This is a very common question also in interviews that what is the actual difference between TestNG Listener and Webdriver Listener.

Let’s discuss now- When we talk about TestNG Listener we will use ITestListener Interface.

This interface has some methods which we need to override as per our requirement.

Recently I posted a video on youtube about Listeners hope it will help.

For example- take some method of ITestListener

1-@Override
    public void onFinish(ITestContext arg0) {
                
    }

 

 2-    @Override
    public void onStart(ITestContext arg0) {
        
       
    }

 

 3- @Override
    public void onTestFailure(ITestResult arg0) {
        

    }

etc..

How to implement TestNG Listener

Its not that tough as compared to WebDriver Listeners we simply have to implement ITestListener interface and override all method as per requirement and its not required that you should have some statements in all methods but yes you should use some of that method Wisely

Scenario-

1-If testcase is failing then what action should be performed

2- If testcase is skipped then what should be action requested and so far..

Step 1- Create a simple class and implement ITestListener listener

Step 2- Override all unimplemented methods

Once you implement all your java program will look like

package testngDemo;

import org.testng.ITestContext;
import org.testng.ITestListener;
import org.testng.ITestResult;

public class ListenerDemoExample implements ITestListener{

    @Override
    public void onFinish(ITestContext arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onStart(ITestContext arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onTestFailedButWithinSuccessPercentage(ITestResult arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onTestFailure(ITestResult arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onTestSkipped(ITestResult arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onTestStart(ITestResult arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void onTestSuccess(ITestResult arg0) {
        // TODO Auto-generated method stub
        
    }

}

So let me implement some of the methods and I will start my test.

I will override following method onTestStart, onTestSuccess(), onTestFailure()

I have written a small test for facebook login and I am failing this testcase forcefully so that we can check how different events will be fired if testcase pass or fail

Program

package testngDemo;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.ITestContext;
import org.testng.ITestListener;
import org.testng.ITestResult;
import org.testng.annotations.Test;

public class ListenerDemoExample implements ITestListener{

    // This is dummy tescase for facebook login
    @Test
    public void loginFB(){
       
        WebDriver driver=new FirefoxDriver();
        driver.get("http://www.facebook.com");
        driver.manage().window().maximize();
        driver.findElement(By.id("email")).sendKeys("mukesh@facebook.com");
        driver.findElement(By.id("wronglocator")).sendKeys("dont-tell");
        driver.findElement(By.id("loginbutton")).click();
    }
    
    
    
    
    @Override
    public void onFinish(ITestContext arg0) {
        // TODO Auto-generated method stub
       
    }

    @Override
    public void onStart(ITestContext arg0) {
        // TODO Auto-generated method stub
       
    }

    @Override
    public void onTestFailedButWithinSuccessPercentage(ITestResult arg0) {
        // TODO Auto-generated method stub
       
    }

    @Override
    public void onTestFailure(ITestResult arg0) {
    
        System.out.println("Screen shot captured====="+arg0.toString());
       
    }

    @Override
    public void onTestSkipped(ITestResult arg0) {
        // TODO Auto-generated method stub
       
       
    }

    @Override
    public void onTestStart(ITestResult arg0) {
        // TODO Auto-generated method stub
        System.out.println("TestCase started====" +arg0.toString());
       
    }

    @Override
    public void onTestSuccess(ITestResult arg0) {
        // TODO Auto-generated method stub
       
        System.out.println("Congrates Testcase has been passed===="+ arg0.toString());
       
    }

}
 

 Step 3- It not completed yet now we need to modify our xml file that is known as testng.xml and we have to specify this listener and we have to execute that xml file only.

We have predefined listeners tag so that we will use today.

<listeners>
<listener class-name="testngDemo.ListenerDemoExample"/>
</listeners>

so your complete testng.xml file will look like.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="none">
<listeners>
<listener class-name="testngDemo.ListenerDemoExample"/>
</listeners>
  <test name="Test">
    <classes>
      <class name="testngDemo.ListenerDemoExample"/>
    </classes>
  </test> <!-- Test -->
</suite> <!-- Suite -->

Step 4- Simple run this testng.xml file and analyze the output

Now if you analyze above output this event automatically getting triggered like once testcase start and testcase failed or testcase pass.