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Regression Testing vs. Unit Testing: A Detailed Comparison

Summary: Today, every enterprise wants quality and bug-free software. To achieve this a variety of tests are performed on software such as unit tests, integration tests, regression tests, etc. All these tests are very important to ensure that software remains bug-free and performs as expected. Let’s now understand two of these software testing methods in detail.


What is regression testing?

Regression testing is an important software testing type that revolves around re-running the functional and non-functional tests. A regression test is done to verify that the existing product remains unaffected after frequent code changes or updates. It helps to check that the previous functionality of the software works as expected even when new features are added or code changes have been introduced.

Regression Testing

What is unit testing?

Unit testing is a software testing method, where individual units of the software are isolated and tested. It is done to check that each unit of software works as expected. Unit testing is the first level of software testing. It is performed by developers during the development or coding phase.

Unit testing

Regression test vs. unit test: A detailed comparison

Point of ComparisonUnit TestingRegression Testing
When is it performed?It is performed in the coding/development stage and is the first level of the software testing process.Regression testing is performed at all levels. It is performed whenever any code changes are made in the software.
Who performs it?Performed by developers, testers, QAPerformed by QA and software testers
Why is it performed?It is performed to ensure that the smallest possible units of the software work as expected in isolationIt is performed to ensure that the existing functionality of the software remains unaffected whenever changes in the code are made.
What are its different types?A unit test is of three types: Black boxWhite boxGrey boxThe regression test is of seven types: Corrective regression testRetest-all regression test Selective regression testProgressive regression testComplete regression test Partial regression test Unit regression test  
How is it performedUnit testing can be done in two ways: manual and automated.   Steps involved in the unit test are: Developers first write the code in the application.Then developers isolate the code and perform a unit test by using unit testing frameworks and tools. Then results are analyzed and failed test cases are reported.Regression tests can either be manual or automated. However, companies prefer automated tests. Steps involved in automated regression test are: Analyze  the changes in softwareAnalyze impact resulting from these changesDefine regression testing strategyBuild regression test suiteExecute regression tests at different levels – unit, integration, functional, and system  
What tools/frameworks are used?Some of the commonly used unit testing frameworks are NUnit, JUnit, TestNG, Jtest, PHPUnit, HTMLUnit, etc.Some of the commonly used regression testing tools are Selenium, Ranorex Studio, Katalon Studio, TestSigma,  TestComplete, Watir, etc.

Conclusion: Unit tests and regression tests are two very essential software testing methods that help to ensure the quality and reliability of software. The unit test helps to determine the functional correctness of units of software whereas the regression test helps to determine that software functionalities remain unaffected after frequent code change and updates. Both software testing practices are important for quality software. Leverage regression test from a next-gen QA and software testing services provider to achieve high performing, high quality, and reliable software.

About the author: I am a technical content writer and I write articles on various IT related topics. In this article, I have tried to share my views on a detailed comparison between regression testing and unit testing.


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