The Basics of Regression Testing

Published on
May 25, 2023
Tessa McDaniel
Marketing Team Lead

Regression testing is a vital part of making sure that your product hasn't lost its mind every time a release goes through.

Regression testing is critically important when it comes to testing software. It's all about making sure that when you make changes or updates to an app or system, everything still runs smoothly. You don't want any unexpected issues popping up! In this article, we're going to dive into the basics of regression testing. We'll talk about the different types of regression testing, why it's so important in Agile and CI/CD environments, when you should do it, and some cool techniques to make regression testing a breeze. So, let's get started!

What Is Regression Testing?

Regression testing is all about retesting an app or system to make sure that the features that were working before are still working even after changes are made. It's double-checking to see if any new bugs popped up or if things got messed up along the way. The goal is to keep the system intact and make sure that any modifications or updates don't mess with the existing features. So, think of running regression test suites as a way to ensure that everything stays smooth and glitch-free even after making changes.

Types Of Regression Testing:

Unit Regression

Unit regression testing focuses on unit tests, or testing components of the system after modifications to ensure that the changes or new product features did not introduce any regressions within the product whole.

Partial Regression

Partial regression testing is like a focused version of regression testing. It zooms in on specific units of code that have undergone changes and makes sure they're still playing nicely with the rest of the unchanged code.

Complete Regression

In complete regression testing, the entire regression testing suite is executed to validate the entire system, including both modified and unaffected areas.

Visual Regression

Visual regression testing (which can be viewed as an honorary regression testing type) compares visual representations of an application before and after changes to identify any visual inconsistencies or regressions. 

Why is Regression Testing Important?

In Agile teams and CI/CD environments where rapid development and frequent releases are common, the regression testing process plays a vital role. It ensures that new changes do not introduce regressions or break existing core functionality. By conducting regression testing at a higher frequency (like functional tests), dev teams can maintain a high level of confidence in the stability and reliability of the software. It helps in minimizing the risk of unexpected issues and ensures that the product maintains its quality standards throughout the development lifecycle.

When Is Regression Testing Done?

Regression testing should be performed at various stages of the Software Development Life Cycle, including:

  • After bug fixes or patches are applied
  • After introducing new features or enhancements
  • After performing system upgrades or migrations
  • Before major releases or deployments

Regression Testing Techniques

These are just a few types of regression testing that testing teams run.

Retest Everything

When it comes to retesting everything, it's exactly what it sounds like: going back to the starting line and rerunning the entire test suite after every single modification. This approach leaves no stone unturned and provides comprehensive coverage. However, it can be quite time-consuming and resource-intensive, as it requires executing all the tests from scratch.

Regression Test Selection

Regression test selection takes a more targeted approach. Instead of retesting everything, this technique involves selecting specific test cases from the test suite based on the areas that have been impacted by the changes. By narrowing down the focus to the affected areas, it reduces testing efforts while still ensuring adequate coverage.

Test Case Prioritization

When it comes to test case prioritization, it's all about making smart choices. This technique involves identifying and prioritizing the test cases based on their importance and the likelihood of being affected by the changes rather than running the entire suite of regression tests. By focusing on critical functionalities and areas that are more susceptible to change, regression testing becomes more efficient. It ensures that the most crucial aspects of the application are thoroughly tested while optimizing resources.

Progressive Regression Testing

Progressive regression testing is when new test cases are written each time the product requirements get adjusted. This sounds needlessly time-consuming, but it actually ensures that the regression suite is still relevant and functioning when those requirements are changed. The goal is no flaky tests!


Regression testing plays a vital role in the software testing process, acting as a safeguard for the stability and integrity of an application or system. Its primary purpose is to catch regressions, those pesky bugs or issues that resurface when changes are made through the development process. By conducting thorough regression testing, development teams can identify and address these regressions early on, preventing them from making their way to end users. 

Virtuoso runs visual regression tests to ensure that every pixel of your web app is perfect so you can rest easy knowing that your quality product stays on-brand and your users all have a consistent user experience. Plus, automated visual regression tests can catch every detail that a manual testing team could miss. If you want to see for yourself, give our free, two-week trial a spin! 


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