JUnit vs. TestNG: Which One Should You Use for Test Automation?

Writing reliable JUnit tests and TestNG tests is essential for delivering error-free software. When choosing a unit testing framework, developers often face a common question: Should I use JUnit or TestNG?

Both JUnit and TestNG play a critical role in automation testing. They help developers run tests, catch bugs early, and ensure that software behaves as expected. However, each framework has its own strengths and limitations.

This detailed guide will walk you through everything you need to know about JUnit vs. TestNG, including:

✅ What is JUnit?
✅ How to Set Up JUnit for Automation Testing
✅ What is TestNG?
✅ How to Set Up TestNG for Automation Testing
✅ Key Differences Between JUnit and TestNG

Let’s get started! 🚀

What is JUnit?

JUnit is a popular unit testing framework for Java applications, widely used for unit tests, functional tests, and integration tests. It follows a straightforward approach, making it easy to write and execute JUnit test cases using annotations like @Test. Over previous versions (JUnit 4, JUnit 5), it has improved test configuration, assertion methods, and execution of tests, making it a strong choice for testing frameworks.

JUnit follows the Test-Driven Development (TDD) approach, where tests are written before the actual implementation. This ensures that code is built correctly from the beginning, reducing debugging efforts later. It is also commonly used in automated testing frameworks alongside Selenium and REST Assured.

Key Benefits of JUnit

• Automated Testing for Java: Helps run unit tests automatically, reducing the need for manual verification.
• Easy Assertions: Comes with built-in assertion methods to compare expected and actual results.
• Integration with Build Tools: Works seamlessly with Maven, Gradle, and CI/CD pipelines.
• Supports Test Runners: Allows executing test cases individually or in bulk.
• Used in Multiple Testing Levels: Supports unit testing, integration testing, and even functional testing.
• Strong Community Support: Being an open-source framework, JUnit has extensive documentation and a large user base.

JUnit ensures that every piece of code behaves as expected, making it an essential tool for Java developers and QA engineers working on automation testing solutions.

Test Setup of JUnit

Setting up JUnit is fairly simple and follows a simple approach. Whether you’re working on a Maven project or a standalone Java application, JUnit can be quickly integrated.

To use JUnit for test automation, you need to install dependencies, write test cases, and execute them. Here’s how to set up JUnit from scratch:

1️⃣ Install JUnit

JUnit is available in different versions:

🔹 JUnit 4: The most stable and widely used version.
🔹 JUnit 5: The latest version with modular architecture and extended features.

📌 Install JUnit in a Maven Project

For Maven users, add the following dependency in the XML file under the dependencies tag:

📌 Using JUnit in a Standalone Java Project

For non-Maven/Gradle projects, manually download the JUnit JAR file and add it to your Java classpath.

2️⃣ Create a JUnit Test Class

A JUnit test class should be inside the src/test/java directory.

• The @Test annotation indicates that the method is a test case.
• Natural assertions like assertEquals help compare expected and actual results.
• The method must be public void, ensuring JUnit can recognize and execute it.

3️⃣ Run JUnit Tests

To execute JUnit tests in Maven, use:

mvn test

JUnit will automatically detect all test methods and execute them. If the test passes, you’ll see ✅ SUCCESS. If it fails, ❌ FAILURE with error details will be displayed.

JUnit also supports dependent methods, where one test depends on another. For example, a public void login method might need to run before executing other test cases. JUnit allows structuring such dependencies between tests, ensuring a well-organized testing process.

JUnit supports time constraint handling through the public void timeoutDemo feature. If a test should fail after a specific duration, it can be written as:

This ensures the test fails if it exceeds the time limit of 1000 ms.

JUnit provides a detailed guide for writing different test types, from JUnit parameterized tests to handling exception test feature cases. Since testing matters, it's essential to explore these functionalities for building a robust test automation framework.

4️⃣ JUnit Annotations You Should Know

Below are a few JUnit annotations:

These annotations simplify test case writing by allowing you to set up pre-test and post-test conditions efficiently.

What is TestNG?

TestNG (Test Next Generation) is a powerful Java testing framework built to overcome JUnit’s limitations. While JUnit is great for unit testing, TestNG is more flexible and supports end-to-end test automation, including UI testing, API testing, and integration testing.

Unlike JUnit, it provides additional functionalities such as dependent tests, exception test features, input parameters, and data-driven testing using testng data providers. It is widely used in automation projects for handling complex dependencies between tests.

With a huge test suite and a vast user base, TestNG allows customized test reports, parallel execution, and method dependency control. It supports a variety of annotations, making it an ideal test automation framework for large-scale applications. Many testers prefer TestNG in Selenium automation testing due to its flexible test configuration and enhanced reporting.

Key Benefits of TestNG

• Parallel Test Execution: Runs multiple tests simultaneously, improving execution speed.
• Built-in Reporting: Generates detailed HTML reports without additional tools.
• Test Dependencies Support: Allows defining dependent tests using dependsOnMethods.
• Data-Driven Testing: Supports parameterized tests using @DataProvider.
• Flexible Test Configuration: Lets you define tests in testng.xml instead of using annotations alone.
• Better Exception Handling: Provides more control over handling expected failures.

TestNG is widely used in Selenium automation testing, API automation, and regression testing due to its ability to handle complex test scenarios efficiently.

Test Setup of TestNG

Setting up TestNG is similar to JUnit but comes with additional annotations and flexible test configuration options. It involves installing dependencies, writing test cases, and executing them. Here’s how to set up TestNG from scratch:

1️⃣ Install TestNG

TestNG is available as:
🔹 Maven/Gradle dependency (for automation projects).
🔹 Eclipse plugin (for manual execution).

📌 Install TestNG in a Maven Project

For Maven projects, add this dependency inside pom.xml:

📌 Using TestNG in a Standalone Java Project

If you're not using Maven/Gradle, download the TestNG JAR file and add it to your Java classpath.

2️⃣ Install TestNG in Eclipse

1. Open Eclipse → Go to Help → Eclipse Marketplace.
2. Search for TestNG and click Install.
3. Restart Eclipse after installation.

After installation, TestNG will be available in the Run Configurations.

3️⃣ Create a TestNG Test Class

Create a test class inside src/test/java:

Unlike JUnit, TestNG doesn’t require methods to be public void—they can have any access modifier. This is a slight difference that makes TestNG more flexible.

4️⃣ Run TestNG Tests

You can execute TestNG tests in different ways:

✔ From Eclipse: Right-click the test class → Select Run As → TestNG Test.
✔ From Maven: Run:

mvn test

✔ Using testng.xml:

Create a testng.xml file in the project root:

Then, execute it using:

mvn test -DsuiteXmlFile=testng.xml

TestNG tests can be run via Maven, command line, or TestNG XML file.

5️⃣ TestNG Annotations You Should Know

TestNG provides a variety of annotations, such as:

These annotations provide better control over test execution, making TestNG ideal for large-scale test automation frameworks.

Differences Between JUnit and TestNG

When choosing between JUnit and TestNG, understanding their differences is essential. Both are popular frameworks in the automation testing community and offer unique features. JUnit is widely used in unit testing, whereas TestNG provides more flexibility, making it suitable for integration testing, system testing, and even automation testing tools like Selenium.

Let’s break down the major differences in annotations, parallel execution, dependency management, assertions, and reporting to help you choose the best framework for your automation tests.

Annotations in JUnit vs TestNG

Annotations simplify test execution by marking specific test methods, setup methods, and teardown methods. JUnit and TestNG have distinct annotations with slight differences in their functionality.

JUnit Annotations:

JUnit uses @Test, @BeforeEach, @AfterEach, @BeforeAll and @AfterAll for structuring tests. These annotations allow users to initialize and clean up test environments efficiently.

Example:

import org.junit.jupiter.api.*;


public class JunitAnnotationsExample {
 
    @BeforeAll
    static void setup() {
        System.out.println("Executed once before all test cases");
    }


    @BeforeEach
    void init() {
        System.out.println("Executed before each test case");
    }


    @Test
    void testMethod() {
        System.out.println("Test case execution");
    }


    @AfterEach
    void cleanup() {
        System.out.println("Executed after each test case");
    }


    @AfterAll
    static void teardown() {
        System.out.println("Executed once after all test cases");
    }
}

TestNG Annotations:

TestNG provides similar annotations but with more control, such as @BeforeSuite, @AfterSuite, @BeforeTest, @AfterTest, @BeforeClass, @AfterClass, @BeforeMethod, @AfterMethod, and @Test.

Example:

import org.testng.annotations.*;


public class TestNGAnnotationsExample {


    @BeforeClass
    public void setup() {
        System.out.println("Runs before any test method in this class");
    }


    @Test
    public void testMethod() {
        System.out.println("Test case execution");
    }


    @AfterClass
    public void teardown() {
        System.out.println("Runs after all test methods in this class");
    }
}

Key Takeaways:

• JUnit has fewer annotations and follows a structured approach.
• TestNG supports more flexible test configurations and offers suite-level annotations.
• TestNG’s dependency management and parallel execution make it preferable for large-scale automation projects.

👉 Further Reading: JUnit Official Docs | TestNG Documentation

Parallel Test Execution

Running multiple tests simultaneously can reduce execution time and increase efficiency, especially in Selenium automation testing.

JUnit Parallel Execution:

JUnit does not support parallel execution natively. However, it can be achieved using third-party tools like Maven’s Surefire Plugin or JUnit 5’s built-in parallel testing features.

Example (JUnit 5 Parallel Execution in junit-platform.properties file):

junit.jupiter.execution.parallel.enabled = true
junit.jupiter.execution.parallel.mode.default = concurrent

TestNG Parallel Execution:

TestNG has built-in support for parallel execution, making it ideal for large test suites and automation testing services.

Key Takeaways:

• JUnit requires additional setup for parallel execution.
• TestNG provides built-in support for parallel execution with minimal configuration.
• If your project requires parallel test execution for large-scale automation, TestNG is the better choice.

Dependency Management

Managing dependent tests is essential when dealing with sequential execution scenarios. Some tests may rely on the success of previous tests, and handling such dependencies can be challenging.

JUnit Dependency Handling:

JUnit does not have built-in support for dependent methods. However, users can manually handle dependencies using assertions and conditions.

TestNG Dependency Management:

TestNG supports dependent tests natively using the dependsOnMethods attribute.

Key Takeaways:

• JUnit requires manual workarounds to manage dependencies.
• TestNG allows direct dependency management using the dependsOnMethods feature.
• If your test suite involves interdependent tests, TestNG provides a smoother approach.

Data-Driven Testing

Data-driven testing allows tests to run with multiple sets of input values, making automation testing more efficient.

JUnit Data-Driven Testing (Parameterized Tests):

JUnit provides @ParameterizedTest to run tests with different input values.

TestNG Data-Driven Testing (Data Provider):

TestNG provides @DataProvider, which allows more flexibility in test data management.

Key Takeaways:

• JUnit provides @ParameterizedTest, but it has limited flexibility.
• TestNG’s @DataProvider supports multiple input sets in a structured way.
• If data-driven testing is a priority, TestNG is the better choice.

Assertions 

Assertions verify whether a test passes or fails.

JUnit Assertions:

JUnit offers assertion methods like assertEquals, assertTrue, assertFalse, assertNotNull, assertArrayEquals.

TestNG Assertions:

TestNG has similar assertion methods

JUnit vs TestNG: Key Differences

JUnit and TestNG are both widely used frameworks for test automation, but they cater to different testing needs. While JUnit is lightweight and well-suited for unit testing, TestNG offers advanced features such as parallel testing, data-driven testing, and better dependency handling, making it ideal for complex test automation scenarios.

The table below highlights the key differences between TestNG vs JUnit to help testers choose the best framework for their needs.

Which One is More Popular?

Both JUnit and TestNG have strong adoption in the test automation community, but their usage depends on the type of testing projects they are applied to.

• JUnit is widely used in Java-based unit testing frameworks and is integrated into many development stages of software projects.
• TestNG has gained popularity in automation testing services due to its parallel testing, exception test feature, and dependency testing capabilities.
• JUnit 4 and JUnit 5 remain common for unit testing, but the TestNG framework is often preferred in Selenium automation testing and large-scale automation projects.
• Both frameworks are open-source unit testing frameworks, but JUnit has a longer history, while TestNG provides a wider variety of features.
• The choice often depends on project needs—JUnit for simple unit tests, and TestNG for suite testing and cross-browser testing.

If we compare GitHub repositories, Stack Overflow discussions, and Java projects, JUnit remains the most commonly used framework for unit tests, while TestNG dominates the Selenium and enterprise testing space.

When to Choose JUnit?

JUnit is the best-suited framework when the primary focus is unit testing. It provides a straightforward approach for JUnit testing and is widely used in test-driven development (TDD) for Java applications. It is simple, efficient, and works well for repeatable automation tests.

✅ Use JUnit when:

• Writing unit tests for Java applications with JUnit framework.
• Following a TDD approach where tests are written before the code.
• Working on small to medium-sized projects with minimal dependencies between tests.
• Integrating with build tools like Maven projects and Gradle, where JUnit tests are seamlessly supported.
• Writing quick, isolated tests using JUnit annotations like @Test, @Before, and @After.
• Avoiding complex test configuration and focusing on natural assertions like assertEquals.

📌 Example:
A Java developer working on a Spring Boot microservice may prefer JUnit for unit testing service components. Since JUnit integrates well with Spring’s testing framework, it simplifies testing by using JUnit assertions and public class test cases for verifying service logic.

When to Choose TestNG?

TestNG is an ideal test automation framework for handling complex automation testing projects. It is widely used in Selenium automation testing, providing flexible test configuration, exception test features, and parallel execution. It allows testers to manage dependent tests, data-driven testing, and generate customized test reports.

✅ Use TestNG when:

• Performing integration testing, functional tests, and end-to-end testing.
• Running Selenium WebDriver tests for cross-browser testing and login functionality.
• Using parallel execution to run tests across multiple browsers.
• Managing dependencies between tests using dependent test features like public class DependentTest.
• Implementing data-driven testing with TestNG data provider and handling sets of input dynamically.
• Generating detailed HTML/XML reports with complete test logs for better debugging.
• Avoiding code duplication by using reusable test methods and lists of objects as test inputs.

📌 Example:
A QA engineer working on an e-commerce web application would benefit from TestNG’s parallel execution to run multiple browser tests simultaneously. By utilizing method dependency and exception test features, they can ensure robust Selenium automation testing, reducing overall test execution time while maintaining high testing standards.

Final Thoughts

Both JUnit and TestNG are powerful testing frameworks, but they serve different purposes.

• Choose JUnit for unit testing and TDD-based development.
• Opt for TestNG if working on Selenium automation, complex test suites, or large-scale testing projects.

For Java developers, JUnit is the go-to choice for writing fast, reliable unit tests. For automation testers, TestNG provides more control, flexibility, and scalability.

People Also Ask

Which tool is mostly used for automation testing?

Selenium is the most widely used automation testing tool, especially for web applications, due to its open-source nature and cross-browser compatibility.

Does Selenium use JUnit?

Yes, Selenium supports JUnit for writing and executing test cases, but TestNG is often preferred due to its better test management and reporting capabilities.

Is JUnit included in Spring Boot?

Yes, Spring Boot includes JUnit by default in its test dependencies, making it easier to write unit and integration tests.

Which features are not supported by JUnit?

JUnit lacks parallel test execution, built-in dependency management, and advanced data-driven testing, which are available in TestNG.

Is TestNG a BDD framework?

No, TestNG is not a BDD framework; it is a testing framework. For BDD, tools like Cucumber and JBehave are used instead.