What Is Regression Testing And Why Do You Need It?


5 min read

June 20, 2022

In this article, we cover the basics of regression testing in software development to show you how it can eleva

and also, many times simply helps you to avoid some irritating bugs or malfunctions. Since we already have settled that testing in fact is your good friend in the world of programming, now is the time to talk about different kinds of tests you can find out there.

Regression Testing – How Does It Work?

There’s a huge variety of tests used in software development. Some of them are performed during the production and some others - when the production is completed. Regression testing belongs to the second type: it’s done to verify that the changes applied to the code during software development phase didn’t impact the existing functionalities of the product. This is to ensure that the product works well with the new functionality or with bug fixes applied to the existing code. Previously executed test cases are run again to verify the impact of this change.

What Kind of Regression Testing Techniques Are There?

Retest All

This one is the most accurate, yet the most expensive method of them all. In retesting, each test case is checked once again to confirm if all of its parts are working as intended.

Regression Test Selection

This method is an alternative to the expensive Retest All technique. In this case, QA doesn't run all of the tests, but instead divides them into three categories: reusable, retestable, and obsolete test cases. In addition, RTS (Regression Test Selection) might actually create new test cases that haven’t been run before yet might be relevant.

Test Case Prioritization

This technique aims to maximize the number of bugs detected through regression tests and to do so at the lowest cost. Every test case is assigned a priority, and then all of them are performed one by one, starting from the most important ones and finishing with the least important ones. Thanks to that, even if there’s not enough resources to perform all of them, the ones that should detect the most flaws will already be performed and should give us some answers.

Hybrid Approach

Sometimes it’s best to combine the best of both worlds: Regression Test Selection and Test Case Prioritization. With the hybrid approach, QA can mix the desired features from both techniques, focusing on what’s the top priority for them, to get the best results.

What Should You Go With? Manual or Automated Testing?

Though most software development companies are well aware of the problems that might arise due to the lack of QA, there seems to be a lot of confusion around choosing the best QA testing model. Manual tests are definitely cheaper to develop, but more expensive to conduct, especially in the larger projects. As a result, many organizations opt for the automation of this process. Automated tests take far more time (and therefore costs) to develop, but once they’re developed, can be run non-stop. Aside from the reduction of the time required to execute repetitive tests, automation also offers greater precision and less conduct errors than manual testing. Automated tests also provide easier reporting.

To sum up, in small projects there may not be a need to develop automated testing. However, in bigger ventures, it may be counterproductive to stick only with manual testing. Also, testers' performance can decrease with time, since the process is long, repetitive, and – frankly – quite boring

We still recommend regression testing (automated or manual), because as your software grows, the risk of new features affecting other parts of it grows proportionally.

Let’s not forget about the Pesticide Paradox. Its principle states that: if the same set of test cases are executed over and over again during a period of time, then these sets are not capable of identifying any new defects in the system anymore.

In order to overcome this issue, the set of test cases needs to be regularly reviewed and changed. The new test cases can always be added and those not capable to find any more errors - are deleted from the system.

Is It Everything I Should Know About Regression Testing?

Surely not! In this short article, we’ve covered the basics of regression testing, but we hope that this portion of knowledge at least has sharpened your appetite for more. If it did, or if you find yourself confused, don’t be shy and contact us – we'll be happy to answer your questions.

Created by

Dariusz Żelasko


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