TEST NG in Selenium?

It is an Automation Framework that provides a set of annotations to create and execute a test script.

It provides a structured approach to writing code that is easily understandable by automation developers.
it provides a test script, test code, and annotation to write a program.
It is upgraded from Web Driver and a modified form of JMeter.
TestNG Command, Locators are similar to Web Drivers.
TESNG Provides HTML Test REPORT With all Test methods separately.
Type of Annotation:-
@Test // it represents Test Method
@Test
void fun1()
{

}

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@BeforeTest:-

This annotation will be executed before the Test Method, It will be declared only once in one Test Class.
@AfterTest:-

This annotation will be executed after the execution of all Test methods .it will be declared only once in one test case.
@Test:-
It is used to create a Test Case Method, We can create more than one test case method to represent different functionality.
@BeforeMethod:-
It will be executed before each Test Case method.
@AfterMethod:-
It will be executed after each test case method
Before Execute this code first install TestNG in Eclipse IDE Tools:-

click to this article:-

.Install TestNG

package scs;

import org.testng.annotations.*;

public class Hello {

@BeforeTest

public void fun1()

{

System.out.println("before Login Test Case");

}

@Test

public void fun()

{

System.out.println("Login Test Case");

}

@AfterTest

public void fun3()

{

System.out.println("after Login Test Case");

}

}

Example of BeforeTest, AfterTest, and Multiple Test Method with Priority:-

package scs;
import org.testng.annotations.Test;
import org.testng.annotations.BeforeTest;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.AfterTest;
public class TestCaseDemo {
WebDriver driver;

  @Test(priority=2)
  public void f() {
System.out.print("Test");
driver.get("https://accounts.google.com/signin");
driver.findElement(By.id("identifierId")).sendKeys("test.surtel@gmail.com"); 
driver.findElement(By.xpath("//span[@class='RveJvd snByac']")).click();         
driver.manage().timeouts().implicitlyWait(50, TimeUnit.SECONDS);  
driver.findElement(By.xpath("//input[@type='password' and @class='whsOnd zHQkBf']")).sendKeys("surtel@123");
driver.findElement(By.xpath("//span[@class='RveJvd snByac']")).click(); 
  }

  @Test(priority=1)

  public void f1()
  {
  driver.get("http://newtours.demoaut.com/");
    }

  @BeforeTest
  public void beforeTest()

 {

  System.out.print("Before Test");
  System.setProperty("webdriver.chrome.driver", "C:\\chromedriver.exe");
  driver= new ChromeDriver();
      driver.manage().window().maximize();
  }
  @AfterTest
  public void afterTest() {
  System.out.print("After Test");
  driver.close();
  }
}
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Examples of BeforeMethod,  AfterMethod,  BeforeTest, AfterTest, and Multiple Test methods with priority.

package scs;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;
public class TestCaseDemo2 {
  WebDriver driver ;
  @BeforeTest
  public void f1()
  {
System.setProperty("webdriver.chrome.driver", "C:\\chromedriver.exe");
driver= new ChromeDriver();
     driver.manage().window().maximize();
  }
  @BeforeMethod
  public void funDisplay()
  {
  driver.get("http://newtours.demoaut.com/");
  System.out.print(driver.getTitle());
  }
  @Test
  public void f() {
  driver.get("http://newtours.demoaut.com/mercuryunderconst.php");
  System.out.print(driver.getTitle());
  }
  @Test
  public void f2() {
  driver.get("http://newtours.demoaut.com/mercuryregister.php");
  System.out.print(driver.getTitle());
  }
  @AfterMethod
  public void funDisplay2()
  {
  driver.navigate().back();
  driver.navigate().refresh();
  }
  @AfterTest
  public void f3()
  {
driver.close();  
  }
  }

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@BeforeClass:-

This annotation will be executed before TestMethod Execution means it will be executed BeforeTest annotation also.

@BeforeClass Annotation will be declared once in a single class always.

@AfterClass:-

This annotation will be executed after the execution of all test methods .it will be declared once in a single class.