Introduction to TestNG for Selenium Automation | Setup, Advantages, and First Test

What is TestNG?

TestNG is a testing framework used to organize, execute, and manage automated test cases.
It is heavily used with Selenium WebDriver.

TestNG provides:

• Test grouping (Smoke, Regression, Module-wise)

• Test execution ordering & prioritization

• Parallel browser execution (runs tests faster)

• Data-driven testing (DataProvider support)

• Better reports

In short:
JUnit is okay for unit tests.
TestNG is built for real automation frameworks.

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Why TestNG is Preferred Over JUnit (Real Industry Reason)

Feature	JUnit	TestNG
Parallel Execution	Difficult	Very easy (parallel="classes")
Grouping Tests	Limited	Powerful & clear grouping support
Data Providers	Not built-in	Built-in DataProvider annotation
Reporting	Basic	Detailed HTML + XML reports
Executing multiple classes easily	Manual setup	testng.xml handles everything

Interview tip:
Scalability is the REAL reason.
Automation frameworks in companies may contain hundreds of test cases — TestNG handles them cleanly.

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Installing TestNG — Full Setup Guide

We’ll cover both IDEs, because students use both:

• IntelliJ IDEA

• Eclipse IDE

We will also handle both Maven and Non-Maven projects.

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✅ If You Are Using IntelliJ IDEA (Recommended)

Step 1: Create a Maven Project

File → New → Project → Maven → Next → Finish

Step 2: Open pom.xml and Add TestNG Dependency

<dependency>
    <groupId>org.testng</groupId>
    <artifactId>testng</artifactId>
    <version>7.10.2</version>
    <scope>test</scope>
</dependency>

Step 3: Let IntelliJ Download Libraries

Right Click on project → Maven → Reimport

or simply wait for IntelliJ to auto-resolve dependencies.

How to Verify TestNG was added:

Project → External Libraries → testng-7.x.jar should appear

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✅ If You Are Using Eclipse

Step 1: Install TestNG Plugin

Help → Eclipse Marketplace → Search “TestNG” → Install → Restart Eclipse

Step 2: Create Java/Maven Project

File → New → Maven Project

or

File → New → Java Project (Non-Maven)

Step 3 (Maven Case): Add TestNG Dependency in pom.xml

Same as IntelliJ.

Step 3 (Non-Maven Case): Download TestNG Manually

1. Go to: https://testng.org

2. Download .jar

3. Add to Build Path:

Right Click Project → Build Path → Configure Build Path → Add External JARs

Verify Installation

Create class → Type @Test → Press Enter → It should auto-import from:

import org.testng.annotations.Test;

If this import is suggested → TestNG is installed successfully.

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✅ Your First TestNG Test (Same in IntelliJ & Eclipse)

import org.testng.annotations.Test;

public class FirstTest {

    @Test   // Marks this method as a test case
    public void testExample() {
        System.out.println("TestNG is working!");
    }
}

Explanation Table

Code Part	Meaning
@Test	Tells TestNG to treat this method as a test case
testExample()	Test method name (you can rename based on scenario)
System.out.println(...)	Simple output to confirm execution

Run This Test

• IntelliJ: Right click → Run ‘FirstTest’

• Eclipse: Right click → Run As → TestNG Test

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✅ Output Example

TestNG is working!
PASSED: testExample
===============================================
Total tests run: 1, Failures: 0, Skips: 0
===============================================

This confirms TestNG is successfully installed and working.

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Understanding How TestNG Executes Tests

When you run the test:

1. TestNG searches for methods marked with @Test

2. Executes them in alphabetical order (unless priority is defined)

3. Generates a test result report

This is how TestNG controls execution.

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Recommended Folder Structure (Real Selenium Framework)

src
 └── test
     ├── java
     │     ├── tests        ← All test cases
     │     ├── pages        ← Page Object Model classes
     │     └── utilities    ← Helpers: WebDriver, config, waits, logs
     └── resources
           └── testng.xml   ← Controls groups, suites, parallel runs

This is the exact structure used in real companies.

Why This Matters

This structure:

• Keeps test cases organized

• Separates UI page elements from test logic

• Makes framework scalable for real projects

This is the structure interviewers expect you to know.

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Where TestNG Fits in Automation Architecture

Selenium → Talks to Browser
TestNG → Controls Testing Flow
Java → Implements Logic
Jenkins/GitHub Actions → Runs tests daily
Allure/Extent → Reporting Layer

Think of:

• Selenium = Driver

• TestNG = Project Manager

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Interview Questions from This Topic

Question	Correct Good Answer Approach
What is TestNG?	Test automation framework used for organizing, grouping & executing tests efficiently. Supports parallel execution and data-driven testing.
Why use TestNG instead of JUnit?	More scalable, supports test grouping, prioritization, parallel runs, better reporting, and DataProviders.
What is testng.xml used for?	To configure and execute test suites, groups, and parallel executions without changing code.

Does TestNG replace Selenium?

No. Selenium handles browser automation; TestNG controls test execution.

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