What is Regression Testing ?
What Do We Do In Regression Check?
Why Should Regression Testing Be Automated?
Getting started with regression test automation
Automated Regression Testing in Agile: What, why, and how?
How to Make Automated Regression Testing Cost-Effective?
Advantages Of Regression Testing
Types & Techniques Of Regression Testing
How To Perform Regression Testing?
Who should perform Regression Testing
Codeless Automated Regression Testing Tools
How Much Regression Testing Is Required?
Regression Testing vs Functional Testing
Regression Testing vs Sanity Testing
Regression Testing vs Unit Testing
Regression Testing vs Smoke Testing
Types of Regression Testing
How to select test cases for regression testing?
Must-have features for automated regression testing tool
"Regression" literally means "the return to a former or less developed state." So, any testing done to catch regressions in software functionality is called Regression Testing.
Regressions in the code can occur due to bug fixes, new features added to the code, or changing requirements. Regression Testing aims to test all the code that could be affected by recent changes. It ensures that new changes do not introduce new bugs in previously-tested and bug-free software.
Regression Testing is often used interchangeably with Retesting, but testers should remember that retesting and regression testing are different. Learn more about the differences between Regression Testing and Retesting.
During a sprint cycle, developers, testers, and stakeholders focus on the quality of new functionalities instead of testing previously-developed, stable software for bugs. However, end-users will still use existing functionalities as much as (if not more than) the new ones. Any new functionality must integrate and work seamlessly with the previously-tested and stable software. However, post-integration, the new functionalities can introduce bugs that affect the functionality of the previously-tested and stable software.
Regression Testing catches these bugs before they slip into production. It ensures that your end-users continue to get the same—if not better—quality experience that they had before the release of new functionalities.
Regression test cases are basically your previously-created functional tests. Once new functionality is thoroughly tested and deployed, its functional tests become part of your software's larger regression test suite. To track the creation and execution of these test cases, use a requirement traceability matrix.
Continuous Testing in a CI/CD pipeline automatically catches the bugs at the build stage. To do this, you need a test automation tool that integrates seamlessly with your CI tools.
Regression test suites grow with each new functionality you add to your software. Over time, regression test suites can become so large that manually executing those tests within the tight deadlines of Agile sprint cycles is no longer possible.
Since Regression Testing needs to be repeatable and recurring, it's best suited for automation. You can run a complete regression check before every release and create leaner, fast feedback test suites to test for regressions after changes (hotfixes) to the code.
It's inadvisable to jump into regression test automation without a clear understanding of the costs that will go into it. Poor or hasty test automation quickly becomes non-deterministic or flaky, requiring more developer and QA hours to fix and critically endangering quality.
If you are new to test automation, automating your regression tests will require:
Learn the best practices for effectively automating your regression testing.
Learn more about the challenges of automating Regression Testing in an agile environment.
You can automate regression tests in several ways with different tools. Here are a few tools and their test automation approaches:
It is an open-source and cloud-based platform that lets you create automated regression tests in simple English, either manually or through a record-and-playback approach. It also has AI that auto-heals elements and identifies regression-affected tests.
This tool has an IDE called Katalon Studio that supports creation of test cases in JAVA and Groovy. It also has a Katalon Recorder.
Selenium is an open-source browser automation driver. You can use it in different programming languages to automate regression test cases for your websites.
Ranorex lets you automate regression tests in multiple programming languages and through a recorder.
When you follow the Agile software development methodology, you push new changes to the product in every sprint. The expected output for a sprint is a working deliverable. Regression testing is done at the end of every sprint to ensure that the new changes work with the existing product.
Teams who move to automation start by automating regression tests because manually testing for regressions at the end of every sprint:
Before adopting automation, you must carefully decide how to automate the regression tests. High-priority test cases should be automated first, starting with the automation of smoke and sanity test cases . If some parts of your product are unstable or prone to frequent changes, you can safely exclude their testing from your regression suite automation.
While Agile methodology speeds up the development process, it poses some challenges to regression testing automation. One of our blog posts covers automated regression testing challenges in Agile and ways to overcome them.
Most Agile teams automate their tests in n-1 sprint automation. Essentially, tests are automated once a sprint is already dev-done. This practice can create automation backlogs over time. In-sprint automation is the smartest way to begin regression test automation without turning it into a parallel development project. It ensures that everything developed in a sprint has corresponding automated tests created within the sprint. Read about the challenges of in-sprint automation of regression testing.
A test automation framework is the set of rules, a predefined structure or guidelines that the automated test cases should follow. It is essential to have the structure in place for the best outcome of the test automation activity.
For the automated regression testing of the UI to be economically feasible, there are few points that should be considered before automation is put into place:
Experts have tried to come up with as many as 7 types of regression testing, but, on a broad level there are only 2 types of regression testing:
Complete Regression Testing:
This is when a complete regression test suite is executed. There could be multiple scenarios in which this is done:
Partial
Regression Testing:
This type of testing is done when only a portion of the regression test suite is executed. This can be done in multiple scenarios as listed below:
The kind of regression testing being pursued decides the way the test cases for regression test cases are selected for execution. Also, read more about the iteration and full regression testing in agile.
According to the type of project and its needs, different regression testing techniques can be employed as listed below:
Regression Testing can be manual or automated. If the number of test cases are small in number, it can be managed in less time manually too but if the number of regression test cases is large, automated regression testing is the ideal solution. The goal is to automate the regression test suite here.
All the test cases that were created for stable features are added to the regression test suite. When automated, all the test cases added to a regression test suite can be executed after every change as the testing will be automated and the time taken would be less too.
Testers who have not tested the feature before but are capable of executing the documented test cases. In such cases, the documentation should be up to the mark for newbies.
Testers who may not have executed the functional tests but have good knowledge about the features that need regression testing and can catch any major bugs, if any, introduced in them.
Testers who previously executed the functional tests for the features that need to be regression tested.
Testsigma allows you to automate test cases in simple English. Thus, it can be easily learnt and understood by non-technical members of the team too and can help jumpstart the automation of regression testing.
According to the type of project, the regression testing strategy can be decided. Example: If the project has a lot of development work going on in parallel, it will be a good idea to do a regression test once all the development work is completed.
If the project is such that there won’t be much time for regression testing at
the
end, regression testing will have to be executed after every change.
Here, selective regression testing will be needed, for which:
Framework will have to be defined for regression testing keeping below points in mind:
Best Practices for achieving best results are:
There are many applications that have an elaborate UI and need UI regression testing
to
be automated for best performance at all times. There are many automated testing
tools
that offer codeless automation of UI regression testing.
Some of the popular codeless automation testing tools are:
Selenium - record and play feature(Selenium IDE) can be used here to achieve codeless automation.
Sikuli - Python-based GUI automation tool, uses image recognition algorithm for element selection.
Katalon - very similar to Selenium, and its record and play feature can be used to achieve codeless automation.
Testsigma - An ideal automated regression testing tool that suggests relevant or affected test cases after a feature enhancement/bug fix. Testsigma lets you run regression tests right after the first check-ins, automatically, within a sprint.
SeeTest - A mobile automation tool that supports image-based as well as object-based recognition.
Test.ai - AI-powered bots that generate and execute test cases for testing UX of a mobile application.
Read details on Selenium Alternative for Automated Regression Testing here.
There could be 2 solutions:
There could be multiple approaches that could be adopted according to the need of the project and focusing on the optimum use of resources:
Have the regression test suite ready and decide how much time the complete execution will take.
Execute this regression test suite after all the changes are included and tested functionally and the next thing to do is release!
Of course, this is not a solution if quick deployments need to be done after a few fixes.
After a fix - a bug fix, a new feature integration or some change in the requirements, do an impact analysis of the change.
And according to the change and the time allotted for regression testing specific to that fix, execute the high priority test scenarios.
Read the details on how to decide when to start regression testing and when can it be considered complete.
While Regression Testing makes sure that there are no regressions in a product in related areas after a bug fix or a change, functional testing ensures the functionality of a product is according to the requirement specifications.
Regression Testing can include both functional testing and non-functional testing. Usually, it is the test cases created during functional testing that are included in the regression test suite once the functionality being tested becomes stable.
So, eventually functional testing becomes a subset of regression testing.
For more details on Functional and Regression Testing, read here .
Sanity testing is performed on an existing software build when there is an addition of new modules or code changes are done. Sanity tests ensure that the build is stable enough to carry out the next levels of testing such as end-to-end testing on it. When sanity testing is passed on a build it is taken forward for further testing, else if it is failed then the build is rejected for further levels of testing. It is also known as surface-level testing.
Regression testing is performed to check if code changes or modules addition have impacted the existing working functionalities/code of the software. Regression testing is detailed testing which is a superset of sanity testing.
| Feature | Regression Testing | Sanity Testing |
|---|---|---|
| Goal | It is detailed testing where the whole application is checked, with emphasis on the impacted areas where changes have been made. | Only a few functionalities where there are code changes are tested. |
| Planning | It is a planned testing activity where detailed test cases are written. | It is not planned and detailed test cases are not written. |
| Timelines | It takes longer to execute the regression tests as the whole application is tested usually for weeks. | It takes only a few days to execute sanity tests. |
| Subset | It is a subset of existing functional test cases. | It is a subset of regression test cases. |
Unit testing is performed on individual units/modules of the software to check that they are independently working as expected. Regression testing ensures that the new code changes have not hampered the working of the already existing and working code.
| Feature | Regression Testing | Unit Testing |
|---|---|---|
| Goal | To check the entire software is working as expected and new code changes have not affected the existing code. | To check the individual units of code are independently working as expected. |
| Execution stage | Executed later in the development cycle when there are code changes or bug fixes. | Executed early in the development cycle as and when the code is developed, unit by unit. |
| Coverage | Covers the whole application or software. | Covers a single unit at a time. |
Smoke testing is performed on initial builds of a product to check that the core functionalities of the product are working fine. If the smoke testing fails, then the build is rejected, sent back to developers to fix, and no further testing activities are performed on it. Therefore, it is also known as build-verification testing.
The major difference between smoke testing and sanity testing is that smoke testing is performed on initial and unstable builds of the application. However, sanity testing is performed on stable builds of an existing product.
| Feature | Regression Testing | Smoke Testing |
|---|---|---|
| Goal | To detect bugs that may have slipped in due to recent changes in the existing working code. | To approve or reject the initial build of a new application/product for further levels of testing. |
| Timelines | Takes longer to execute and therefore expensive to conduct. | Takes less time and results are announced immediately. |
| Scope | Whole application/software is tested. | Only core/basic functionalities are checked. |
Read a blog about the differences between sanity, smoke, and regression testing here.
It is the simplest regression testing type because it is executed by reusing the existing test cases. It is used when there are no major changes in the code, and therefore there is no extra effort required in writing and executing the regression test cases.
During selective regression testing, we do not execute the whole regression test suite. Based on the modules where there are recent changes, regression test cases are picked and executed.
It is executed when a new piece of code is merged with existing code in the software. It is executed to verify that the product is working as expected after adding a new unit of code.
It is executed when there are multiple and major changes in the code that might have impacted the core code of the product. It helps to uncover unexpected failures and bugs and then the final product is ready for release.
When there are changes in software specifications or new test cases are added to the testing suite. Then, there is a requirement to create and add appropriate regression tests, this is progressive regression testing.
Most complex type of regression testing, it tests all the functionalities in detail from the scratch. All existing test suites are rerun to complete retest-all regression testing, therefore, it is very time-consuming.
Regression testing is absolutely crucial for the success of any product, and therefore the selection of proper regression test cases is imperative. The below points are beneficial to pick relevant regression test cases.
Wherever there are most recent code or functionality changes, that area should be covered under regression testing.
In an application, there are modules that are prone to bugs and are frequently fixed, it is important to keep that covered in regression testing.
The basic functionalities of the product should behave as expected, therefore regression test cases should be picked from such modules.
The modules which have a high impact on business are treated as high-priority. They should be included in the regression test suite to bypass any bug miss which may cause irreversible harm to the business.
Integration tests check the interaction and dependencies of modules with each other, any bug missed here will prove crucial. Therefore, it is important to include the integration tests and other complex test cases in the regression test suite.
No bug should be present on UI or client-facing modules, therefore regression test cases should be picked from such modules as well.
Here are 9 tips to select perfect regression test cases.
Check our blog here for more details.
Whenever there are some changes introduced to some part of the code in the application under test in the form of bug fixes, enhancements, changes in requirements or features, there is a probability that some functionalities in the related areas of the code could be impacted.
Thus, the objective of Regression Testing is to make sure that the features and functionalities, that were tested to be stable before a change was made in code, continue to be stable even after the changes.
Regression Testing could be automated or could be performed manually depending on what processes are adopted by an organization for a product. If automated, the regression testing will necessarily be performing the same steps again and again.
But if done manually, the testers can use common sense to not repeat the same steps for all the test cases and try variations of it to uncover any new bugs.
Regression Testing can surely be automated. To proceed with automation make sure below 2 conditions are met:
Application under test is planned to be under active development for a long time
The number of regression test cases for the application under test are quite a lot such that it will take a long time to execute manually.
If the regression test cases are automated, much time won’t be lost even if all the test cases were executed. Thus, in such a scenario, how much regression testing does not need to be thought about.
But, if the test cases are not automated and time is a constraint - which usually is - the best way to go about it by following below steps:
Analyse the change and the impacted areas because of the change
For the impacted areas, execute high priority test cases
For the application as a whole, execute the critical test scenarios before any deployment or release
Regression Testing is absolutely essential to minimize the number of issues reported by customers post release. But there are times when the managers and stakeholders don’t realize the importance of regression testing and thus, don’t assign the time for it.
Being a tester, below are few things that can be done:
Discuss the importance of regression testing with your management and project stakeholdersWith every change testing - try to execute at least the critically important test cases for impacted areas.
Before every release - create a release checklist that includes execution of the most important workflows that a customer will go through for sure.
When possible, automate the regression test cases.
During the SDLC(Software Development Life Cycle), features are added to a product incrementally. Once a feature is tested thoroughly and is deemed stable, the test cases created for the testing of that feature are added to the regression test suite that will be executed when further changes will be made in the application in the future.
The test cases in the regression test suite can be easily automated as these are stable and the process of automating them is called regression testing automation.
When the code base for the product is huge and there are a lot of test cases that need to be executed for regression testing, automation saves precious time, efforts and resources that would be spent on doing the testing manually otherwise.
Automated Regression Testing reports any errors quickly in a matter of hours which might have taken days if the testing was done manually.
When done manually, humans could skip some test cases because of being new to the functionality or shortage of time or just by genuine mistake. Automation makes sure no minor functionality is missed.
To save on time, for regression testing, manual testers decide on test cases according to priority while when automated all the test cases that are automated can be run any number of times, often after every single change. Thus, the quality is in check at every moment.
Regression Testing involves execution of test cases corresponding to stable features and functionalities for an application. These test cases need to be executed multiple times, sometimes after a change in the code in the form of bug fix, enhancement, new feature, change in requirement.
Because these test cases need to change rarely and are executed multiple times during the SDLC(software development life cycle) for a project, they become a perfect candidate for automation
Agile development focuses on development in iterations, thus testing is also done in iterations. But, the end result for each of these iterations is a working deliverable. To be able to have a working deliverable at the end of every sprint, it is essential to do regression testing before the end of every sprint.
There is no right or wrong answer to this question.
There are organizations that don’t give so much importance to testing as compared to the speed of deployment and thus there are times when regression test automation is not a part of DevOps. But, even then there are organizations that have understood the part that regression testing plays in maintaining overall quality of a product and thus, have integrated it into their DevOps.
Now, as people are becoming more and more aware about maintaining quality of an application, experts are advising companies to include regression test automation under DevOps to enhance quality feedback loop.
