What Is Regression Testing in Software Testing?

by Anna Khrupa on Apr 18, 2022

Regression testing is a technique that is used to further elevate the quality of a software product. Find out what it is and when it is done within the software testing life cycle.

Regression testing is a type of software testing that deals with the recent changes to the software code and makes sure that those changes do not negatively affect the existing functional and non-functional features of the product.

Regression testing is hardly ever used on a brand new software product. It only makes sense when the product has gone through several iterations, the QA team has found some bugs and the development team has fixed them, or after new functionality was added to an existing product.

Why is regression testing important?

Regression testing is an essential quality measure in the software development process. It helps the development and QA teams avoid the situation where a recently discovered bug is fixed, but the solution has triggered another bug.

When a software product frequently undergoes revisions or new functionality is regularly added to it, regression testing helps maintain the quality of the product on an adequate level and avoid customer backlash from unresolved issues.

When is the right time to do regression testing?

Regression testing does not have a fixed place in the software testing life cycle. Routine regression tests need to be performed every time there is even a minor change in the software code or a new feature has been added. A final regression test is typically performed on the software build that is going to be shipped to the customers even if there haven’t been any changes in the code recently.

Regression testing vs. retesting

Regression testing and retesting are two of the most commonly confused types of software testing. Both of them take place after significant changes in the code and both of them are performed to assess the possible effect of the changes on the existing code.

Despite their similarities, regression testing and retesting are not the same. The goal of regression testing is to make sure that no new bugs have been triggered by the recent code changes or the addition of new features.

Retesting, in turn, is done to make sure that the bugs that were once discovered and fixed have not reappeared after the code was altered. Ideally, testing a software product after a code update should be done in the following sequence:

There is a change in the code.
The QA team performs regression testing to test the existing functionality.
A bug is discovered.
The QA team fixes the bug.
Re-testing is done to see whether the bug reappears.

Regression testing and retesting are not mutually exclusive and are both essential components of a thorough software testing strategy.

How to do regression testing

In order to achieve the desired results and thoroughly test the software product for regressions, a QA engineer must follow a standard procedure for running regression tests. These are the three essential phases of the regression testing process:

Selecting test cases. The nature of regression testing requires repeatedly using the same test cases and seeing whether they will have a different outcome. This is why the job of a QA engineer at this stage is to select the most relevant test cases. The two primary directions to go here are testing the areas that have been recently altered and checking the areas that are particularly prone to defects.
Selecting the right tools. Regression testing can sometimes be done manually for maximum precision, but automated regression testing helps increase test coverage in less time. Depending on the area being tested, the QA engineer can opt for functional testing tools, unit testing tools, or API testing tools.
Running the tests. The more thorough the preparation process for regression testing has been, the more effective the tests are going to be and the more comprehensive results they will yield. At this stage, it’s also very important to painstakingly document every step of the process and its outcome. This will not only give a complete idea of the product’s possible regressions, but will also make it easier to do subsequent regression tests.