How to use TestNG with Selenium WebDriver

(The precondition for this tutorial that the Selenium WebDriver is already installed.)
Firstly go to TestNG website’s download page, and follow the instructions to install the TestNG plugin to Eclipse. (http://testng.org/doc/download.html)

After the TestNG was installed, create a new java class file (without main method).

Create the setUp() function. To this function you can put that the WebDriver use for example the Firefox browser, and for example that the driver get the desired webpage.

This function will start before the test. To ensure that, before the setUp() function need to put @BeforeClass annotation.

@BeforeClass: The annotated method will be run before the first test method in the current class is invoked.

If you use only one test in the java file then you can use the @BeforeTest annotation too.

@BeforeTest: The annotated method will be run before any test method belonging to the classes inside the <test> tag is run.

If you have more than one test in the java file, better to use @BeforeClass annotation to set up the WebDriver, because it not economical to initialize the WebDriver before every test. It’s enough only once before the class.

You can use the @BeforeTest annotation beside the @BeforeClass for example to get the desired webpage.

When you write a TestNG annotation before the function, you need to import the TestNG annotations to the file. Just click to the annotation or to the red x before that, and select :
Import ‘Test’ (org.testng.annotations)

Beside the @BeforeClass we need an @AfterClass annotation too.
Use this annonation with tearDown() function. The tearDown() function is used to quit form WebDriver.

You can use @AfterTest annotation with the same logic as @BeforeTest.

Before every test you must use the @Test annotation.
The @Test annotation marks a class or a method as part of the test.

After the test was written, you can run the test with the following steps:

When the test is finished you can check the result in the Console tab or/and in the TestNG tab in Eclipse.

Here is a simple example code how to use TestNG with the Selenium Webdriver:
(The test open the Wikipedia page, click to About link and write out the About page title.)

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class TestNGSeleniumTest {

// create a WebDriver
WebDriver driver;

// use the Firefox browser and go to the wikipedia site
@BeforeClass
public void setUp(){
driver = new FirefoxDriver();
driver.get("http://en.wikipedia.org/wiki/Main_Page");
}

// quit from WebDriver
@AfterClass
public void tearDown(){
driver.quit();
}

@Test
public void testFindElements()throws Exception{

//find the About link
WebElement about= driver.findElement
(By.xpath("//*[@id='n-aboutsite']/a"));

// click to the link
about.click();

// wait for 5 seconds
Thread.sleep(5000);

// write out the title of the page in console
System.out.println(driver.getTitle());

}
}

If you want more information about TestNG then check out the documentation in the TestNG website: http://testng.org/doc/documentation-main.html