In this definition guide, you will learn what is regression testing. Regression testing is a testing methodology that ensures previously developed software code and features continue to work properly while retesting new code and features. This is vital in software development as it confirms changes to code have not caused unintended adverse side-effects.

“Regression testing ensures that older code and features still work while retesting the newly added code and functionality making sure it works as well with the existing code.” -Source: How AI is transforming software testing?

In fast Agile development lifecycles, software code is updated often. There are times when defective code can reappear in production due to either human error or poor revision control. Proper regression testing at the QA stage before production can catch these issues. Alternatively, a fix for one part of the code can inadvertently cause bugs in another part of the application.

For example, if we launch feature A it might break B. In practical terms, say we are building an e-commerce website, and change the search feature then break the item purchase flow. That’s where the regression happens. That is why we want to perform full regression testing because we cannot be fully sure one feature inadvertently affects another. Sometimes this can be overlooked by humans. However, machines could catch this flaw and notate with it screenshots for QA testers later on in a report. This is just one, of many, features in AI-powered test automation tools like Autify.

To avoid errors like this, it is a great coding practice to document any bugs and regularly run them through regression tests. To reduce possible human errors, it is best to use automated testing tools rather than manually running them. With a well-prepared test plan, you can use such tools to automatically execute test cases. Some DevOps teams schedule tests right after compilation, nightly, or even weekly.

Takahiro Yoshii, a QA (Quality Assurance) manager at SMN Corporation shared his experiences with regression testing. He stated, “there are times when adding new features causes problems for existing functions and causes regression. Of course, the more features you have, the more likely regression will be. The test itself will become complicated too.” He goes on to add, “it’s not uncommon to find a bug and have to check for regression. You start forgetting how much of the regression testing needs to be done manually.” He elaborates, “we are reaching that point, and it was becoming increasingly difficult to handle it manually.”

By implementing Autify for their regression testing solution, they would end up saving 40 to 80 man-hours per month. Takahiro mentions, “something that used to take 40 hours now takes virtually zero hours. A task that one staff used to spend a whole week doing is now entirely automated. The 40-hour saving happens once or twice a month.” This was valuable time that staff could be spent on other tasks Yoshii explains.

Common Regression Testing Principles

Regression testing can be tiered into three common principles based on the testing scenario:

  1. Retest All – this technique requires the most time and resources which could consume more man-hours. It requires retesting all tests in the testing queue. More on this later…
  2. Regression Test Selection – instead of retesting the entire test stack. They can be split into categories: “Reusable Test Cases” or “Obsolete Test Cases.” The former can be reused in future test scripts, whereas, the latter cannot.
  3. Prioritization Of Test Cases – literally means just that. This principle allows for selecting tests based on the highest priorities to the business use case(s).

The first principle in the list often causes confusion. Here is when to apply one over the other…

Re-testing vs Regression Testing

For newbies in automation testing. These two terms can sound conflicting. However, they are different.

Re-testing means testing again. As mentioned, this is the most time-consuming part as the entire application may not require a complete retest- only the parts that changed. Yet it offers more peace of mind knowing the entire application is working as expected. I would recommend re-testing periodically.

Regression is only performed on the part(s) of the application that changed. This can significantly reduce QA testing times. I recommend this method to be used very often.

What are some benefits of Regression Testing?

One of the greatest benefits of regression testing, when executed properly, is ensuring a stable product and new feature releases are brought to market faster.

The other is cost savings which can benefit the organization. Recall the three testing principles above. Instead of retesting the entire application, a QA manager can select portions of the test bucket or suite to test faster and cheaper.

Why is maintaining Regression Tests challenging?

Maintaining regression tests can become challenging, especially with frequent UI and functionality changes or at scale. It also can grow to be one of the most time-consuming and resource-intensive portions of software development.

In current web UI technology, identifiers like ‘id’ and ‘class’ attributes are often easily changed by design and function. Changing these typically break test scripts. We have written a guide detailing how this can be problematic. If the DevOps team is dependent on manual human intervention, this can become costly. Hence, why AI and automation are necessary and changing the landscape for software testing.


It has been proven that having an effective regression strategy in place can save time and money in software development. Equipped with the correct tools, bugs can be identified quicker and eliminated from resurfacing later. Though, the more important goal is to produce better products, and faster.

If your organization is seeking a tool that automates tedious regression testing, give Autify a try! We have a 14-day free trial of the platform.