Software development is a broad process with a well-structured flow of phases like analyzing, designing, coding, developing, testing, and deployment. Delivering a product that is up to the mark is only ensured in the testing phase. Testing is the process of checking the functionality of a product to ensure it runs as per customer requirements and expectations.

Testing is an important phase of the software development life cycle (SDLC) and can be achieved either manually or automatically. Whereas, there are multiple categories of testing. One of the examples is to categorize it based on testing levels, like unit tests, integration tests, and system tests. Unit testing is a reliable form of testing which involves testing each piece of the software’s code.

What is Unit testing

Unit testing is performed at the development stage on the tiniest bits of code in the software product. Therefore, it means testing the smallest piece of code, and that helps us with easing out the debugging process and faster development. Unit testing aims to check if the quality of each component of the code is working as expected. Unit testing is always performed first before integration testing and system testing.

To perform unit testing, there are multiple tools available in the market, like JUnit, NUnit, TestNG, PHPUnit, JMockit, etc. In the Java ecosystem, JUnit and TestNG are the most popular and most preferred unit testing frameworks. Both of these frameworks are easy to use, and while JUnit inspires TestNG itself, a few more functionalities and higher levels of testing are added to it that make TestNG more powerful than JUnit.

What is JUnit

JUnit is an open-source unit testing framework used for writing and running tests. It gets its name from the mixing of Java + Unit Testing. JUnit promotes the idea of “first testing then coding”, which increases the productivity of the programmer and the stability of program code. JUnit framework was initially part of xunit, which represents the family of unit testing. It is a standard framework when it comes to performing testing in Java. Its latest version of JUnit is JUnit5, which was created to overcome the limitation of the previous version.

What is TestNG

TestNG is another popular Java-based testing framework, where NG stands for next generation, and it is more flexible than JUnit. TestNG is inspired by JUnit, but overcomes limitations found in JUnit. It introduces some new advanced functionalities and special annotations that are not supported by JUnit and that make it more powerful and easier to use. These new functionalities include support for parameters, flexible test configuration, annotations, and many more. When it comes to testing, it can be used for almost every category of software testing, like unit testing, functional testing, and integration testing.

Difference Between TestNG vs JUnit

Although there is no significant difference between TestNG and JUnit, they both are the most widely used Java-based automation framework and have their own benefits and drawbacks. Here are the main differences between JUnit and TestNG frameworks.

• Annotations:

Both JUnit and TestNG are annotation-based testing frameworks, and they are similar in nature and behaviour. Annotations used in both the JUnit and TestNG frameworks work similarly.

The following table displays some differences in annotations in JUnit and TestNG.

• Ease of Use:

JUnit 5 is built into various modules, to write test code you need JUnit Platform and JUnit Jupiter. If you want more features like Parameter Test, then you need to add the JUnit-Jupiter-Params module. Whereas, TestNG uses a Single module to get all TestNG features. Hence, TestNG is easy to use

• Data Provider:

JUnit Supports multiple ways to provide test data, such as Enum, CSV, CSV Files, etc. whereas TestNG supports data provider methods. Hence, JUnit is better for injecting test methods into input data.

• Test Suite:

Integrating various unit tests and then running them in parallel as a test suite is available for only TestNG, but now it is available in JUnit 5 as well. But the process of implementation is a little different. In JUnit, Test Suite is run using @RunWith and @Suite annotations whereas TestNG uses an XML file to run Suite tests.

• HTML Reports:

To generate HTML reports in JUnit, you need an external plugin i.e. maven-surefire-report plugin. Whereas TestNG automatically creates HTML reports for the test run. At first, TestNG HTML reports look outdated but it’s simple and easy to use. But if you need to share HTML reports with others, use JUnit.

• Assumptions:

Assumptions are a collection of utility methods that support conditional test execution based on assumptions. JUnit supports assumptions to skip tests based on the specific scenario. Whereas TestNG doesn’t support assumptions. Hence, if you want to skip tests based on conditions, use JUnit.

• Test Order:

JUnit does not support Test Order. Whereas TestNG supports Test Order for ordering test methods according to attribute. Hence, TestNG is better when you want to execute tests in a specific order.

• Disable Tests:

JUnit offers many ways to disable and enable tests based on OS, JRE, system properties. Whereas TestNG supports disabling tests but it’s limited in functionality. Hence, JUnit is better if you want to disable or enable tests.

• Parallel Execution:

If you want to run the same test in parallel on multiple threads, TestNG is better for parallel execution as of now with a simple-to-use annotation, while JUnit 5 doesn’t support parallel execution.

Conclusion

TestNG and JUnit are popular frameworks for unit testing. TestNG came after JUnit, with few more functionalities that make TestNG more powerful than JUnit. Additionally, TestNG can perform a bunch of testing, such as integration testing, unit testing, system testing, and much more. Whereas, JUnit is used only for unit testing. So when it comes to choosing the testing framework for your application, it’s better to have a high-level idea of what features are present in each and then select according to your project needs.