Regression Testing

In 2016, Nest Thermostat issued an update that rendered all of its device’s software inoperable. On one of the coldest weekends, customers were asked to cope with the weather. It came out that before upgrading the software, they did not perform proper regression testing.

Testing is frequently ignored or not given the same importance in the software development lifecycle as development. A defective program with many features can cost you more money and a loss of user base, considering testing is just as important as development.

Regression testing becomes essential if you want to create reliable, high-quality applications that encourage user loyalty. Regression testing, its types, procedures, and everything you need to know about it are all covered in detail in this article.

What is Regression Testing? 

Whenever programmers edit or alter their work, the results can be surprising. Regression testing includes evaluating already-released software to ensure that no feature has been broken as a result of a change or addition. Its goal is to catch bugs that might have unintentionally made their way into a fresh build or release version and to ensure that bugs that have already been eliminated continue to be gone. 

You can ensure that any new modifications to an application haven’t led to regression or caused components that previously functioned to fail by re-running testing scenarios that were initially scripted when identified problems were first fixed.

This testing is done to make the product compatible with any added features, error fixes, or extra modifications to current features. Test cases that had already been run, are executed again to make sure that the changes have had impactful effects. 

When to use regression analysis

Regression testing is frequently used in the following situations:

  • An existing feature receives a new requirement
  • The addition of a fresh feature or function
  • The codebase is fixed to eliminate bugs
  • The source code has been optimized to boost performance
  • Patch updates
  • Alterations to the configuration

Why Regression Testing? 

Regression testing is needed whenever the code is altered to determine whether the altered code will have any impact on other parts of the software application. Regression testing is also required when a new feature is involved in the software program. When a performance or functional error is corrected, a regression test can be performed. 

How To Do Regression Testing? 

We must first debug the code to find the errors before we can perform the Regression Testing method. Regression testing is carried out by choosing relevant test cases from the test suite that cover both modified and affected parts of the code after the appropriate modifications are made to resolve the defects.

Enhancements, bug fixes, optimization, and deletion of current features are part of software maintenance. The system might not function properly as a result of these modifications. Regression testing is therefore required. The following methods can be used to perform regression testing:

Retest All 

One technique for regression testing involves re-running each test in the existing test bucket or test suite. Due to the significant time and resources required, this is quite expensive.

Regression Test Selection 

Regression test selection is a technique that tests whether the updated code has any impact on the software application by running a subset of the test cases from the test suite. Test cases are divided into two groups: those that can be reused in subsequent regression cycles and those that are no longer valid and must be discarded.

Prioritize The Test Cases 

Prioritize the test cases based on the importance of the features and their impact on the business. The number of regression test cases will be drastically decreased by prioritizing test cases.

Types Of Regression Testing 

The various type of regression are listed below:

  • Unit Regression
  • Partial Regression
  • Complete Regression

Unit Regression 

Unit Regression occurs during the Unit Testing process, and code is tested independently. A unit regression testing strategy tests code from a birds-eye perspective. This is a straightforward technique where the tester has a list of things to test each time a change takes place. The ideal technique to begin regression testing in an ongoing project is in this manner.

Partial Regression

The project is divided into logical, coherent parts that work with one another to construct the entire application using a partial regression testing approach. Unit regression testing should be carried out on the remaining modules while focusing on the modules that are most important to the application and defining specific test cases for them.

Complete Regression 

Complete Regression Testing, the most comprehensive kind of regression testing, is the last technique. In this situation, one examines the entire codebase to discover any functionalities that could affect usability when breaking and then writes thorough tests for each of them. If used early in the project development, this strategy is time-consuming yet very useful.

Why is Regression Testing Important?

It usually includes creating a test for a well-known bug and running it again following each change made to the code base. This seeks to quickly spot any modification that brings a bug back.

The use of an iterative process is prioritized in the push for software development agility; this involves releasing new code and occasionally breaking things. Regression testing ensures that developers do not break components that already function when they make frequent releases. 

Wrapping Up! 

Regression testing might need some extra resources however it guarantees the significant advantages that make the time and money spent worthwhile. It is an essential component of an agile development cycle that prioritizes output maximization and promises to simplify life for developers and quality analysts, and also ensures to delivery of a positive user experience. 


Shivani Naidu

Shivani is a Technical Content Writer at DCKAP with over three years of experience. After graduation, she landed her first job as a technical writer with QA Touch. She plays an active role within the QA community and manages QA Touch community events. She has developed a unique blend of technical expertise and creative writing skills in collaboration with QA experts.

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