Regression Testing Checklist: Why is It Necessary for Your Software?

Testsigma Inc.
8 min readOct 19, 2023


As the world of software development changes constantly, new technologies continually emerge, and different variations of established technologies diverge from one another. Even an active software undergoes modifications where new features get added or the old ones receive an update. Understandably, minor alterations as such could break several parts of the application that were working fine up until now. Any known changes can introduce an affect on the functionality of existing features. That is when regression becomes important in the testing scenario. And having a regression testing checklist can help you with that process.

Consider this blog as the regression testing checklist that your QA team needs to keep the new features intact with the existing ones.

What Is Regression Testing?

Regression testing is an approach for verifying whether a software system’s new and modified parts still work as expected after being changed.

It checks for bugs and to see if a recent change has broken the existing code. The test should be run in the same manner as the previous baseline test. Regression testing aims to make sure that the rest of the software’s behavior is not affected while the code is being modified.

For example, if a feature that allows users to log in has been changed, you would have to run a regression testing on features related to login. It could typically include checking the sign up function, pre and post login features/actions, and any UI changes on the login page.

How Does Regression Testing Work?

The working mechanism of the regression test includes several techniques. You can rely on these tactics during software testing to ensure that the new changes to the product do not alter the functionality of the existing functions:

  • Test the Whole Software Again

Testing the entire software after altering one or several of its components is one of the techniques of regression testing. This is done to ensure that the altered part of the software works correctly with the unaltered parts. The goal behind running tests for all the important features is to make sure that all the distinct functions/featues of the system work in combination with each other and also independently.

  • Regression Test Selection

Regression test selection is a technique that focuses on selecting the test cases that maximize test coverage. It leads to spending less time and effort on testing as you no longer have to consider all the available tests, but specifically on the ones providing high value.

Let’s explain this idea with an example:

Suppose you have added two new fields to the login page of a website. Besides the usual username and password, now your login page has captcha and OTP field. While you will need to test these two fields with valid and invalid inputs, you will also need to run regression tests for the username and password field. But in this case there is no need to validate the sign up function even though the login page has been modified.

Simply put, out of all the test cases listed under regression, you have to only select the ones that might evidently affect the existing features.

  • Regression Test Prioritisation

Regression test prioritization is the process by which software testing determines the order in which test cases are executed to minimize software defects, taking into account the severity of each defect and the most important features of the system. This helps to determine which test scenarios should be run first and last.

If you have 5 test cases in total apply regression test selection technique to filter the necessary tests. For instance, you have changed the login functionality. In regression testing you would need to test the sign up page and login page UI. Here, the sign up page function would take precedence over UI testing the login page. But prioritizing the test is hugely based on your business requirements and product.

Source: Jelvix

When Can We Perform Regression Testing?

In several cases regression testing comes as an essential part of the testing process. We have mentioned a few scenarios below where you can run regression testing.

  • When new functionality is added to the application

When you add new functionality to an existing program, it can often interfere with previously functioning features and lead to failure in further performance even though the code is written perfectly. For this reason, it’s significant to conduct regression testing to validate that any modifications or enhancements in one part of the application do not adversely affect another part.

  • When the defect is fixed

We can perform regression testing when the defect is fixed. Regression tests verify that the software (or website) continues to work as expected after we fix a bug. A code change needs to be tested to determine whether it has affected any of the other modules and if everything is working as expected.

  • When there is a performance issue fix

Regression testing is often performed to ensure that quality standards are met. It is a process through which we can ensure that the performance and functionality of older code modules remain unchanged upon introducing any newer code versions. Regression testing aims to confirm that any performance fixes in the software have not introduced any new defects or errors.

  • When there is an environmental change

Regression testing follows and verifies successful unit testing, integration testing, and system testing, and it is performed when there are environmental changes. Environmental changes that could trigger regression tests include hardware upgrades, new software versions, and resource constraints, such as memory, disk space, and processor speed.

Difference between Retesting and Regression Testing

The developers will only deliver error-free and valid code if the testing process is done correctly. Retesting and regression testing are two different testing methods and approaches. Both are used for validating software applications; however, their main aim is different.

The term retesting refers to testing the functionality or a bug again to ensure the code is fixed. In contrast, regression testing refers to checking the existing features after introducing changes in software. It is to ensure that the modifications does not produce unexpected negative effects on the existing functionalities.

Source: Utor

Moreover, a considerable difference between regression testing and retesting is the time required to execute each. While retesting can be run immediately after the defect is fixed, regression testing will take several days to complete as it involves rechecking all existing test cases to identify if there are new defects. If a regression test fails, retesting becomes necessary, as this would mean the defect is present in the new build.

How to Perform Regression Testing with Automation?

Source: Simform

  1. Prepare Test Cases

Manual regression tests are performed on the product manually to ensure that certain features, functions, or aspects of the product are working and valid after changes have been applied. Manual testing can be time-consuming because you essentially repeat the same tasks every time a bug is reported. It also requires a lot of resources to be completed.

Automated testing can reduce the number of resources needed and allow you to test and validate your application better and faster. It is performed by tools/testing frameworks and can be integrated with a continuous delivery pipeline. Manual regression testing would be a better idea for a low number of test cases, while automated regression testing will work better if you have a huge pile of test cases that need to be managed. Another aspect you can look at is the frquency of test execution to turn to automation testing to save time on running the same tests again and again.

2. Choose Automation Tools

When making any type of code change or upgrading a part of your application, developers spend a considerable amount of time testing the source code that’s being modified. The difficulty is in finding a way to specifically identify which areas will be affected by the changes to focus your testing efforts. But that’s what really needs to be done!

Otherwise, you might spend a lot of time and effort only to find out that the changes have no impact on the tested parts of your system. This is called “outside-in” testing, and it can help save time and money because you’ll be able to pinpoint better where the problem is.

3. Set the Right Priorities

As the image shows, once you have identofied the areas to run regression testing, next you should focus on selecting the right test cases and correctly prioritizing them. Because no prioritization will result in you spending more time running the test that rarely affect the system. This will either cause you to run out of time (and money) before completing the entire testing cycle or result in a weakened testing cycle as the limited focus is placed on each test case.

The tester should prioritize the tests based on criticality of the functionality.

4. Execute Test Cases

You have the list of test cases and tools, now you only need to combine these two and run the tests. Using the automation tool of your choice, you can develop test scripts, enter the necessary input test data, and receive the test results in matter of minutes. There are some automation tools that require coding knowledge in a certain programming language to create the tests. And there are other tools like Testsigma that can execute your tests in plain English. Testsigma is a no-code test automation tool that efficiently uses the power of NLPs to run your tests.

5. Analyze and Report

All the tests are executed and you have the results with pass/fail status. This step is to understand and analyse those test results to target the features in the application that might be defected. If your tests failed, it clearly means that there are some bugs present in the software. The pass status will mean otherwise. And when you have properly assessed the results, report it back to the concerned teams to work on the issues.


On a web application, the notion of regression testing seems simple enough. Regression testing is a set of tests specifically written after each software update or release to ensure that no new bugs were introduced. This is so important because a bug fix can also cause another bug to surface. In today’s global economy, time is money — and not doing regression testing will cost you dearly. For this reason, to deliver only quality products and updates to your users, you should regularly conduct regression testing to exclude any bugs from your software.



Testsigma Inc.

Testsigma is a completely cloud-based codeless test automation tool that lets you create stable and reliable tests for web, mobile & APIs — all from one place.