How to do Regression Testing

A girl sitting in from of desktop performing Regression Testing

If you are looking for how to do regression testing, then you have landed on the correct article!

In agile, testing must evolve with each sprint, and testers must ensure that new changes do not interfere with the application’s existing functionality. This is referred to as regression testing.

Regression testing ensures that the application’s previous functionality is still functional and that new changes have not introduced new bugs. Regression tests should be used whether there is a small localized change or a more significant change to the software. 

mobile app automation

Teams must ensure that new code does not conflict with older code and that non-changed code continues to function as expected.

There are frequent build cycles in agile, and the application is updated regularly. As a result, regression testing is critical in agile. 

Therefore, a testing team should build the regression suite for successful agile regression testing from the beginning of product development. Along with development sprints, they should continue to improve them.

Why is Regression Testing Important?

It’s difficult for developers to remember all of the intricate ways new code could interact with existing code when writing code for new features. 

Avoiding any potential UI errors slows developers down, making it difficult for agile teams to meet their sprint deadlines. Unfortunately, in many cases, it’s impossible to avoid making mistakes.

However, with a dependable regression test suite, a developer can ensure that a new feature is compatible with all existing functionalities before merging the branch back into the master. 

If the tests uncover any new bugs, they can be fixed before joining the branch. As a result, regression testing serves as a safety net, allowing developers to concentrate on the new functionality they’re creating.

Today, most developers would never consider checking in a new code branch without first performing unit testing. 

Similarly, when new Rainforest developers start, they can’t believe they’ve ever merged a branch or pushed code to production without first regression testing the UI.

Know more: Beginner Guide for Automated Regression Testing Tools

When to Do Regression Testing?

how to do regression testing

It may take some trial and error to find the best cadence for running your entire regression testing suite. However, not every code change is significant enough to warrant running your entire suite.

However, because you’ll be more familiar with the features in the new build and the volume of code you’re testing is smaller, the more frequently you run the suite, the less time it will take to evaluate the results and fix any bugs.

Every time you merge a branch back to master, you should run your full regression suite. If that is not possible, you should still adhere to a few general guidelines. 

In the following scenarios, you should always run your regression suite:

  • When introducing new features to a product (e.g., adding time-tracking to an invoicing app).
  • Following the correction of bugs in an existing feature to ensure that the bug fixes did not introduce new regressions.
  • Following the implementation of a significant software upgrade (e.g., switching to the latest version of Ruby on Rails).
  • Before deploying code to production.

Know more about Regression Testing: Regression Testing; 5 Things To Keep In Mind While Performing It

Best Practices for Regression Testing

#01 Don’t aim for 100% automation

Regardless of how advanced the test infrastructure is, 100% automation is not possible. At the very least, test scripts must be written, and human testers must validate the results. 

In the best-case scenario, 70 to 90 percent automation is achievable because a certain number of test cases will result in false positives/negatives and are therefore unsuitable for regression testing.

#02 Concentrate on the most vulnerable areas of software

Most developers and testers are familiar enough with their software to identify the areas/functions/features that are most likely to be impacted by changes in each sprint. 

Additionally, user-facing functions and critical backend issues must be tested regularly. As previously stated, the collaborative approach to regression testing in agile development aids in this because it includes developers.

#03 Choose Automation

Automation is a must for accelerating regression tests for Agile sprints. Begin with an automated regression test script, then modify it with each new feature. 

As a result, QAs must focus on making incremental changes with each sprint rather than running the tests. 

#04 Know About The Needs of Testers

Keep in mind that testers will need to invest some manual testing effort in the early stages – studying product flow, software logic, UI changes, and so on. 

Automated regression tests are best introduced after the software has been developed and some significant changes have already been implemented. Regression tests should also be interspersed with manual verifications to check for false positives or negatives.

Automated and Regression Testing:

  • Fast-running: Because automated tools can perform certain tasks faster than humans, selecting the right problems to solve with an automated tool can increase the speed with which they are completed. When implementing an automated tool or framework, anything that is highly repetitive and easily automated should be prioritized.
  • Parallel activities: Running automated tools on machines other than the team’s systems allows them to run in the background while other tasks are completed. However, this does not necessarily imply that your team can perform more regression testing in the same amount of time. Plan ahead of time and consider your approach to automation in your regression testing strategy.
  • Targeted feedback: You can use automated tools to work with parts of the system that might be trickier to get to when testing normally. This allows automated tools to potentially give feedback on very specific parts of the product, which will help you target additional regression testing with greater accuracy.

Regression Testing Methods:

  • Re-testing everything entails rerunning all existing tests against the new codebase. This would isolate regressions if the tests were well designed. This method, however, is resource-intensive and may not be feasible for a large codebase.
  • Selective re-testing is sometimes possible to identify a subset of your existing tests that can address all or nearly all of your codebase’s “moving parts.” It is then sufficient to rerun that specific set to find regressions throughout the codebase.
  • Prioritized re-testing—applicable to large codebases. Priority tests focus on code paths, user actions, and areas of functionality that are likely to contain bugs. After these tests have been completed, you can proceed to the next set of tests.

Challenges of Regression Testing:

#01 There are too many changes

Agile methods incorporate stakeholder feedback after each sprint, which is a good strategy for avoiding significant changes later on. 

However, if management and users propose too many changes to product requirements, it may be necessary to rework regression test scripts from scratch in the middle of a project.

#02 Expanding test suites

As new features are added, the scope of regression tests grows with each sprint. As a result, suits can quickly become unwieldy and unmanageable with sufficient automation and team structure.

#03 Pressures of test case maintenance

As test suites grow in size, they must also be maintained, examined, and updated after each sprint. Obsolete tests must be removed, and new tests must be created and added. This can be time-consuming if a project necessitates a large number of iterations.

#04 Communication needs

Testers must maintain constant contact with developers, business analysts, users, and other stakeholders. They require this to become acquainted with the features being developed and user expectations. This may be difficult to achieve and maintain for small teams in particular.

#05 Necessities of skills, knowledge, and frameworks

Automation necessitates testers with technical skills and extensive knowledge of test automation frameworks such as Selenium, Appium, multiple programming languages, and experience running tests in various environments. 

Consolidating a team of such individuals may pose financial and time-related challenges for teams just getting started with Agile development.

Deal Regression Testing with Tool: 10 Best Regression Testing Tools (2022 Exclusive)

Selenium for Regression Testing:

Selenium is an open-source suite of web testing tools. It is now the most popular tool for web testing on both desktop and mobile devices.

Testers can ensure that their web app does not break by running Selenium scripts against web browsers such as Chrome, Firefox, and Safari.

Selenium can be used to perform a wide range of tests, including user interface testing, sanity testing, and regression testing.

Using Selenium for regression testing assists developers in detecting flaws in their web applications before they affect customers. Strategically, such tests aid developers in the modification of code and the introduction of new features.

Selenium regression testing automation frees up testers to focus on problem-solving or more complex types of tests. Furthermore, automation ensures that tests are run methodically and efficiently and that they are not subject to human error.

How To Do Regression Testing In Selenium?

#01 Specify the Requirements

Concentrate on the product and define what is critical for you, the product team, your customers, and other stakeholders.

  • Consider whether you should test only one application or several.
  • When will I run the regression tests – at the end of each sprint or only after significant changes?
  • What constitutes a significant change?
  • When do I need to achieve complete regression coverage?

#02 Examine Possible Use Cases

Use cases will assist you in understanding exactly what you are up against. Begin with a logical description of the tests you intend to cover. Don’t forget about difficult scenarios so that you’re fully prepared.

#03 Establish a baseline

A proper baseline from which to build will allow us to understand where we are.

#04 Select Your Technology Stack

Choosing your tech stack entails selecting a scripting language, a testing platform, and scaling tools. Consider the expected outcomes, inbound and outbound data, and what needs to be covered.

Aside from the standard tapping and scrolling, it would help if you also prepared the following for mobile web testing.

#05 Face ID / Fingerprint ID

  • Network condition simulation (loss of connectivity, insufficient network coverage).
  • Location simulation.
  • Image injection, such as scanning barcodes or QR codes.
  • Injection of audio.
  • SIM-cards
  • Complete control over system settings (i.e., Offline mode, Low battery mode).

#06 Make Tests

Obtain a critical mass of tests and incorporate them into the automation pattern. All of these tests must be atomic and by the overall plan of action. This means they should be able to run independently without relying on other tests.


Regression Testing ensures the least amount of downtime while keeping costs low. Our Regression Testing suite provides that new features or enhancements to the application have no unintended consequences for the application’s current quality. 

Our test teams thoroughly comprehend and analyze the effects of changes made to the test environment and application.

Changes to the test environment can include deployment configuration changes, database updates, and operating system updates, to name a few. Bug fixes, new functionality, functionality enhancements, integrations, patches, and interfaces are all examples of changes to the application.

Regression testing is unquestionably necessary, particularly after introducing new features or changes to software code. Still, it is not recommended to perform regression testing manually because it consumes a significant amount of time and resources and may be inaccurate.

As a result, you should look for automation tools like TestGrid, which provide a smooth experience and allow you to perform complex test cases efficiently. is the ideal automation testing tool for all types of testing, including regression. Furthermore, with features such as an integrated AI system, cloud infrastructure, good security features, integration with almost all software, etc.

And so, if you are in the market for Plug & Play solutions, there could not be a better option for you than TestGrid’s TestOS. Instead of buying licenses for testing services from different vendors, you will get all the services under one roof at a fraction of the cost you would spend otherwise.

You can click here to create your free account and start your testing journey with TestGrid or you may head over to our blog section to learn more!


Q1. What are some good ways of automating regression testing?

Adopt Test Management Software: This is essential for any project larger than a one-developer toy project. You’ll have far more test cases than you’ll be able to track and manage individually. Fortunately, you have a plethora of test management tools at your disposal.

Maintain a Testing Schedule: You should adhere to a strict testing schedule throughout the project. This ensures that the finished project is thoroughly tested. Furthermore, the schedule will encourage the team to become accustomed to a frequent testing regimen.

Create a new failing test for each new bug discovered: Assume your code contains a clear, reproducible bug. However, all of your tests are passing.

That means either your current tests are incorrect or your test suite is deficient in tests. If you find yourself in this situation, create a new failing test to document the problem.

Divide Your Tests Into Smaller Groups: You should divide your test suite into smaller groups. Your test management tool will most likely allow you to categorize your tests. As a result, your team members will be able to identify each type of test quickly.

Q2. When to perform Regression Testing?

To maintain an ideal balance between rapid development and frequent testing, regression testing must be integrated. It is just as important as the development phase in terms of the release process. 

Regression testing is typically used when :

A bug or error has been resolved.
A requirement change is implemented.
A new module or component is integrated into the existing system.
There is a new feature or functionality introduced.

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