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What is software regression testing

Looking for a simple answer to how to prevent software failures? Start by looking at software regression testing—a critical part of software development and one which we sometimes forget is a perfect test automation candidate. 

Software—we can’t live without but is it always easy to live with? At least once in our lives we have experienced software malfunctions causing thousands of flight passengers to be stranded due to software system downtime, or losing access to mobile data services due to software failure or simply being locked out of Social Media due to a software glitch. If we are looking for a simple answer to how to prevent such failures from causing million-dollar damage, we should start by looking at software regression testing as one of the most critical components of a solid product.

Albert Einstein once said:

“A clever person solves a problem. A wise person avoids it!”

Nowadays besides the pure software development companies, almost any other company has to deal with software to a certain extent. Software is literally everywhere—financial institutions, entertainment, real estate, medical care and pharma, automotive companies, universities, governments etc.

If you build software, it is unquestionably important/critical to assure that you maintain its high quality. The best way to assure this is through software testing. One of the components that is a key element of every testing approach and is essential for a good testing strategy is the regression testing. But how should we define regression testing?

So, What Is Regression Testing?

Software regression testing is the testing activity that is responsible for re-running functional and non-functional tests to ensure that previously developed, deployed and tested bits of software still perform as expected after a change.

The closest analogy with a real-life regression testing example I can think of is when you prepare your steak. You normally cook your steak with salt and pepper and always following your favorite recipe from your childhood. One time you decide to add a bit of different ingredients and put garlic and butter—this will cause a shift of flavor of your favorite meal. This would be a regression.

The same logic applies to software regression. Changes in the code while working on delivering a product increment may involve dependencies, defects, or malfunctions. Software regression testing targets the mitigation of these risks, so that the previously developed, deployed and tested code remains stable and operational after new changes.

Why Is Regression Testing so Important?

What do you think following examples have in common?

Windows Locks Out Non-Software Pirates, August 2007

For 19 hours on August 24, 2007, anyone who tried to install Windows was told, by Microsoft's own antipiracy software (called Windows Genuine Advantage) that they were installing illegal copies. If you'd bought Windows Vista, you discovered certain features shut off as punishment. The bug this time was both caused by a human mistake and quite classic: Someone accidentally installed a buggy, early version of the Genuine Advantage software on Microsoft's servers.

Nest’s Smart Thermostat Glitch, January 2016

Google’s Nest was brought down by a software bug during one of the coldest winter nights. The bug—which Nest developers didn’t find until it was too late—drained the device’s battery and deactivated the thermostat. A December software update was the cause, but even when developers fixed the problem, they were left with peeved customers who were less than happy to undertake the nine-step process to reboot the device.

Heathrow Disruption, February 2020

More than 100 flights to and from London’s Heathrow airport were disrupted on Sunday, February 16, 2020, after it was hit by technical issues affecting departure boards and check-in systems, leaving passengers with little information about their flights and limiting the use of electronic tickets.

As these examples, which are true, prove—software glitches sometimes cause costly and embarrassing problems, which highlights the importance of regression testing. If your software has to go through frequent modifications you should definitely spend some time thinking about how to prevent costly mistakes and ensure your product is stable and production ready by using software regression testing.

How to do Regression Testing?

The first step towards software regression testing is impact analysis. This is the process of analyzing the impact of the changes in the deployed application or product. It tells us about the parts of the system that may be unintentionally affected because of the change in the application and therefore need careful regression testing. Once we have done the impact analysis, we choose one of the three most common approaches to regression testing:

  1. Re-test everything. This refers to re-testing your whole system from top to bottom. Test automation suites such Test Studio offer the necessary regression testing tool to perform the majority of the regression tests in an automated, productivity-boosting matter. If your tests are well designed, stable, reliable and optimized for regression testing, this approach will reveal any unwanted regressions.
  2. Selective re-testing. In most cases, it makes sense to limit your testing scope to save time. One way is to re-test only the modified functionality and those parts of your application that are most likely to be affected by the recent changes.
  3. Test case prioritization. With limited test cases, it might be a good approach to try to prioritize those regression tests that could impact both current and future builds of the software.

Automating Regression Testing

Inherently, regression testing is both a time-consuming and a repetitive activity, which often leads to cutting it to the minimum—especially in smaller QA and testing teams with limited capacity. Manual regression testing is used on almost any product, especially early in development. However, despite being the most natural solution in many development environments, it is hardly efficient. This is when test automation comes to hand.

Due to its highly repetitive nature regression testing is an ideal candidate for test automation. Automated regression testing can take care of tedious repetitive tasks and free up time for in-depth exploratory testing, ensuring product increment delivery on time.

The easiest approach to get started with automated regression testing without costly investments and heavy implementation is through using test automation tools. These tools, which with their productivity features are designed with all of the above challenges in mind, help automate web and desktop applications while eliminating technical debt and test flakiness.

Telerik Test Studio is an enterprise UI test automation solution for web, desktop and responsive web applications. It enables QA and test engineers to build powerful and reliable automated tests faster and with fewer hurdles.

Telerik JustMock is a professional grade mocking library that helps you easily craft unit tests even for complex scenarios by isolating dependencies.

Going for codeless test automation or using Test Studio’s code-based automation capabilities—you decide. Whichever approach or blend of both you choose, you’ll always ensure optimal app quality and deliver outstanding automation results for internal and external teams, customers and end users.

Test Studio provides all the necessary features in an all-in-one regression testing tool for your website or WPF application. It integrates easily in any team due to its easy-to-use interface and capabilities, enabling QA engineers and teams, regardless of their technical background or skillset.


Regression testing is essential in maintaining a high quality product and user experience especially when the regression scope grows bigger late in the development cycle. Regression testing tools such as Test Studio can help you easily identify all defects in the early stages of the cycle, and when used with an effective regression strategy, can save you and your organization time and money.  

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Ivaylo Todorov
About the Author

Ivaylo Todorov

Ivaylo is a QA Engineer on the Progress Test Studio team, where he helps build a better and more reliable product. Before starting as a QA Engineer, Ivaylo spent three years as a Technical Support Engineer in Test Studio doing his best to guide customers in their automation endeavours. Ivaylo enjoys skiing, cooking and portrait photography. 

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