What is Regression Testing

January 30, 2023

Testing engineers typically devote a lot of time and effort towards regression testing, and for good reason. Learn more why in this article.

Testing engineers typically devote a lot of time and effort towards regression testing, and for good reason. Learn more why in this article.

Software testing involves many testing approaches, with each individual technique focused towards specific parts, functionalities, or intended uses of the software. One of the most important testing techniques in terms of overall impact on quality is regression testing.

Testing engineers typically devote a lot of time and effort towards regression testing, and for good reason.

During the software development lifecycle, the software goes through hundreds, or even thousands of small or large code changes. During testing, even the smallest code change can have a cascading consequence on the testing protocol. For this reason, it’s vital that the software gets thoroughly tested after one or multiple code changes to ascertain whether it still works according to expectations. This process is called regression testing and it confirms whether any existing functionality of the software has been broken or changed due to changes in code.

The two-fold aim of regression testing is to catch any bugs introduced into the software due to code changes, especially for new software builds, while also making sure that previously found and fixed bugs do not resurface. This often involves repeat runs of tests that have been previously run without issue. Due to this nature of the process, it is referred to as regression testing. Due to the repetitive and time-consuming nature of regression testing, a large part of the process is now usually delegated to test automation.

Let us now delve deeper into the mechanics of regression tests and the importance of the technique when it comes to thorough and reliable software testing.

Understanding Regression Testing

To understand regression testing, it is important to understand that testing of this kind ends up being responsible for the overall quality, functionality, and stability of the software to a significant degree. Software development involves continuous, incremental improvements that are largely accomplished through code changes. Regression testing is the process that makes sure that after every improvement, the software stays viable and sustainable as a unit.

The impact of code changes can get complicated fast as it might involve larger dependencies or the performance of other parts of the software. Malfunctions or defects can start a chain reaction that can have a cascading effect as the program runs, degrading the quality of user experience. Usually, any software would already go through many tests before changes are introduced in the main development branch. The final step of this testing process, one that functions as a failsafe, is regression testing.

Here are some typical use cases which involve regression testing:

  • Source code optimizations for improved performance
  • Codebase changes or fixes to fix defects
  • Configuration changes
  • The addition of a new software feature
  • The addition of an enhancement or a new requirement to a pre-existing feature
  • The addition of bug fixes or patches

Regression Testing and Test Automation

Test automation is an indelible part of the software development process in this day and age. Due to the nature of regression testing, this technique is a prime candidate for automation. If you want better code coverage and high quality standards, reliable automated regression tests are a crucial requirement.

Automated regression testing brings quite a few important benefits to the table. If the regression testing process is rapid and automated, the testing feedback can reach product teams quickly and they can instantly respond to any requirements dictated by that insight. Regression testing is also instrumental for finding newly appearing bugs in the early development cycle of the software. If these bugs build up over time, businesses may have to expend an abundant amount of resources in terms of maintenance costs and human power in order to mitigate the consequences. This throws the importance of regression testing into sharp relief.

The Process of Regression Testing

While organizations have their own unique workflows for regression testing, there are a few generic steps that are usually commonly found in the process.

  1. First, any new features or enhancements are flagged. Once the testing platform detects such a change, it also needs to identify the specific modules or components of the software involved in the change. At this stage, it is also possible to carry out a rudimentary estimation of the possible effect of the new feature or enhancement on the overall features and functionality of the software.
  2. Next, the testing process needs to change to accommodate the recent enhancement or the new feature. This involves prioritizing these changes as a prime target for regression testing, double-checking the product requirements to understand the intended end result of the change, and creating a streamlined, efficient test process to carry out the regression testing with the help of the right testing tools and test cases.
  3. Before regression testing is carried out, it is crucial to determine the appropriate prerequisites and expected behavior. For the prerequisite steps, the software needs to conform to a pre-arranged set of eligibility criteria. For the expected behavior, you need to define the target eligibility criteria for the test to pass and set up minimum conditions.
  4. Finally, all the appropriate test components are duly identified and the test is scheduled for the appropriate time. 

It’s necessary to choose the right one among the regression testing tools, especially when you are looking to heavily automate the process. Certain tools, especially ones that involve the use of AI and machine learning to create self-healing tests, might present an advantage over others.

Regression Testing Techniques

There are many ways to carry out regression testing. The ideal technique will depend on the use case. However, we can define three broad approaches.

1. Prioritizing Specific Test Cases

This is a streamlined regression testing technique that involves working with specific requirements and prioritizing them for testing. Here, you choose a set of specific test cases that you want to run first in the chain. Depending on the use case, the criteria to choose these test cases can involve measuring the failure rate, the overall impact on the business, or the volume of use of the relevant software feature or functionality. Other high-priority test cases can include newly added software features or crucial customer-facing aspects of the software.

2. Segmented Testing based on Potential Problem Areas

For this approach, you pre-select relevant parts of the software that are probable to get affected in some way due to the new feature or enhancement. Then, regression testing can be implemented on these chosen parts of the software only. This can branch out into related areas of the software for better and more reliable coverage. However, by picking and choosing your test cases, you can significantly reduce the time and effort required in completing the testing process.  Compared with the previous approach, where you prioritize specific test cases, here you prioritize specific segments of the software.

3. Complete Regression Testing

This is an exhaustive application of regression testing to every test suite. While this approach requires the most time and effort, it also ensures that all possible bugs get detected and fixed. In specific contexts, this approach might be the best option in spite of its heavy requirements. For example, complete regression testing can be a prudent idea if you are expecting a major platform update or upgrade, or when the software is being rebuilt for a new platform.

Key Takeaways

As regression testing is one sure way to enforce high quality standards and seamless user experience for the end product, its importance cannot be overstated. In agile development environments, regression testing can also bring in a host of broader benefits that affect other important areas of the business. Finally, choosing the right testing tool is crucial for automated regression testing and solutions such as Functionize can go a long way in making the process smoother and more intuitive.

About the author

author photo: Tamas Cser

Tamas Cser


Tamas Cser is the founder, CTO, and Chief Evangelist at Functionize, the leading provider of AI-powered test automation. With over 15 years in the software industry, he launched Functionize after experiencing the painstaking bottlenecks with software testing at his previous consulting company. Tamas is a former child violin prodigy turned AI-powered software testing guru. He grew up under a communist regime in Hungary, and after studying the violin at the University for Music and Performing Arts in Vienna, toured the world playing violin. He was bitten by the tech bug and decided to shift his talents to coding, eventually starting a consulting company before Functionize. Tamas and his family live in the San Francisco Bay Area.

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