What is Regression Testing ?

Iteration Regression Testing

"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.

Iteration Regression Testing

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What do we do in Regression Check?

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.


Testsigma integrates with popular CI/CD tools and sets you up for continuous testing in minutes. Book a demo with our experts to set up continuous regression testing in your pipeline today

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Why should you automate Regression Testing?

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.

Getting started with regression test automation

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.

 

Pre-requisites

If you are new to test automation, automating your regression tests will require:

  • The right tooling: Less than two-thirds of the teams that automate their testing see any RoI due to the upfront and ongoing investment that goes into setting up and scaling a test automation framework from scratch.
  • Skilled resources: If you use test automation tools that require coding (like Selenium, Appium, etc.) for your framework, you'll also need to hire and allocate programmers to develop your automated regression tests.

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Critical considerations before automating regression testing

  • Thoroughly analyze the cost of automation and estimate the ROI in the long run. If your project is of a type that won't require further testing and development post-release, it may not need automation.
  • If you decide to adopt test automation, target test cases that are stable and passing. It saves you the trouble of troubleshooting test cases and prevents any wrong assumptions about the test scenarios.
  • You do not need to automate all test cases. Start by automating test cases in descending order of priority. If there are test cases that will rarely be executed in the real world, leave them out.

Learn the best practices for effectively automating your regression testing.

 

Challenges faced while automating regression testing

  1. Automated regression tests become useless when the application undergoes too many changes within a single sprint, which will make any unchanged regression tests obsolete.
  2. Since new features or enhancements will be baked into the application after every sprint, you must regularly maintain and update regression suites.
  3. Flakiness seeps into your tests when regression tests and test suites are not updated regularly. Flaky tests create false positives and false negatives. As a result, you either lose dev hours trying to find a bug that doesn't exist or let bugs slip through to production.
  4. You cannot automate every test case, but it is best to automate as close to 100% of your regression tests as possible. Striking the right balance between code coverage and functional testing of new features can be challenging.

Learn more about the challenges of automating Regression Testing in an agile environment.

PerfectMind achieves 90% regression test automation with Testsigma

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Automated Regression Testing tools

You can automate regression tests in several ways with different tools. Here are a few tools and their test automation approaches:

Automated Regression Testing Tool Testsigma

Testsigma

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.

Katalon Logo

Katalon

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 Logo

Selenium

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 Logo

Ranorex Studio

Ranorex lets you automate regression tests in multiple programming languages and through a recorder.

 

Automated Regression Testing in Agile: What, why, and how?

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:

  • takes a prohibitively long time, which slows release velocity and leads to a loss of competitive advantage.
  • is prone to human error, which can affect product quality and UX.

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.

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How to Make Automated Regression Testing Cost-Effective?

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:

  • Automation should only be preferred when there will be an ROI in the long term because of this, automation of applications that are supposed to have active development and maintenance for a long time are preferred.
  • Automated test cases should be easy to execute, easy to maintain and any failures should be reported properly and on time.
  • Only those areas should be automated that are not expected to change often.
  • Automation should be high in quality, flaky automated tests are an on-going investment with zero returns.
  • Test cases should be executed on all the different supported devices and screen resolutions to catch important bugs before they reach the customer.
  • The automated testing tool being used should be such that it supports you in saving cost overall, do remember that training, hiring, infrastructure cost and time spent are all costs or investments that go into automation.
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Advantages Of Regression Testing

  • 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, automated regression testing saves precious time, effort and resources that would otherwise be spent on manual testing.
  • Automated Regression Testing reports any errors quickly in a matter of a few hours, which would otherwise take days if tested manually.
  • When done manually, humans could skip some test cases. This could be because they are new to the functionality, or there is not enough time for the following steps, or just due to genuine mistakes. Automation makes sure no minor functionality is missed out.
  • To save time, manual testers may have to limit the test cases executed to high priority ones, while all the test cases that are automated can be run any number of times, often after every single change. Thus, the quality is checked at every moment.

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Types of Regression Testing:

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 Complete Regression Testing:

This is when a complete regression test suite is executed. There could be multiple scenarios in which this is done:

  1. The complete regression test suite is automated and could be executed frequently after any change.
  2. Regression Testing done after many changes that could impact the majority of the application code.
  3. After changes in requirements or functionalities are done that did not require any changes in the existing test cases.

Partial Regression Testing 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:

  1. When there are localized changes that don’t need complete regression testing.
  2. When the project is such that deployments are made quickly after fixes and need partial regression testing to be done to save time.

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.

 

Techniques of Regression Testing

According to the type of project and its needs, different regression testing techniques can be employed as listed below:

  • Re-execution of all test cases in the regression test suite
  • Execution of selected test cases based on impacted areas. Create Test Plan AI Driven Test Automation Software Tool Testsigma
  • Execution of selected test cases based on priority. Read more on how to prioritize test cases here . Edit Test Suite AI Driven Test Automation Software Tool Testsigma
  • A hybrid approach to execute selected as well as prioritized test cases.

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How To Perform Regression Testing?

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.

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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.

 

Who should perform Regression Testing

  1. Who Performs Regression Testing New Testers

    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.

  2. Who Performs Regression Testing Functional Tests

    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.

  3. Who Performs Regression Testing Major Bugs

    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.

Are you looking for a test automation tool that will make your test automation inclusive then yes Testsigma is the tool for you.

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Best Practices For 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:

  • For every change, impacted areas will have to be determined
  • For the impacted areas, high priority test cases will have to be executed

Framework will have to be defined for regression testing keeping below points in mind:

  • Test suites and test cases should be created with a proper structure to facilitate regression testing
  • Pass/Fail report for the test cases should be reported after the execution
  • All the test cases should be assigned priorities Edit Test Suite AI Driven Test Automation Software Tool Testsigma

Best Practices for achieving best results are:

  • If not after every change, regression testing should be performed at regular intervals
  • Impacted areas for all the changes that have been done since the last regression test should be tested
  • All the regression test cases should be up to date
  • High priority and critical test cases should always be executed during a regression test
  • All the bugs caught while a regression test should be reported
  • Regression testing should be done in a way to minimize efforts and maximize results
 

Codeless Automated Regression Testing Tools

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 Logo

    Selenium - record and play feature(Selenium IDE) can be used here to achieve codeless automation.

  • Sikuli Logo

    Sikuli - Python-based GUI automation tool, uses image recognition algorithm for element selection.

  • Katalon Logo

    Katalon - very similar to Selenium, and its record and play feature can be used to achieve codeless automation.

  • Testsigma Regression Testing Tool Logo

    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.

    Affected Test Cases AI Driven Test Automation Software Tool Testsigma
  • SeeTest Logo

    SeeTest - A mobile automation tool that supports image-based as well as object-based recognition.

  • test.ai Logo

    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.

 

How Much Regression Testing Is Required?

There could be 2 solutions:

  • If all the test cases in the regression test suite are automated, then this suite can be run from time to time, preferably after a certain number of changes, because running them after every change could amount to unnecessary test execution.
  • If the test cases in the regression test suite are not automated, they will have to be executed manually. When the application is a big one and has a good number of test cases added to the regression test suite, the decision to execute all of the test cases after every change will not be the best solution.

There could be multiple approaches that could be adopted according to the need of the project and focusing on the optimum use of resources:

  1. 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.

  2. 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.

If you are looking for a tool to quickly automate your regression test suite and be able to execute them everytime there is a change, check out Testsigma!

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Regression Testing vs Functional Testing

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 .

 

Regression Testing vs Sanity Testing

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.
 

Regression Testing vs Unit Testing

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.
 

Regression Testing vs Smoke Testing

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.

 

Types of Regression Testing

  • Corrective

    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.

  • Selective

    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.

  • Partial

    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.

  • Complete

    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.

  • Progressive

    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.

  • Unit Executed during the unit testing phase, where the code is tested in isolation without considering the dependencies it has on other interfaces or units.
  • Retest-all

    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.

 

How to select test cases for regression testing?

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.

  • Modules where there are recent code changes

    Wherever there are most recent code or functionality changes, that area should be covered under regression testing.

  • Most error-prone modules

    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.

  • Core functionalities of product

    The basic functionalities of the product should behave as expected, therefore regression test cases should be picked from such modules.

  • High business priority 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 and complex test cases

    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.

  • Modules which are visible to the end-user

    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.

 

Must-have features for automated regression testing tool

  • Easy test authoring: The automated regression testing tool should allow quick test creation and edits because the number of regression test cases increase every time there is a new feature added and every time there is a release. AI Driven Test Automation Software Tool Testsigma
  • Run Automated Regression Tests after every build: The automated regression testing tool should allow execution of automated regression tests as often as required. For this, the test execution should be quick and easy and should support parallel test execution.
  • Quick Actionable Feedback: The feedback and reports provided by the automated regression testing tool should clearly identify failures and action items to proceed. This helps make regression testing and working on feedback easier.
  • Saves time through Parallel execution: Time is of utmost importance in the software industry and continues to be as the competition in the market increases. Thus, parallel execution becomes an essential element to save the precious test execution time.
  • Prioritize the test cases for regression testing: Most of the time, it is not required to execute all the test cases after every change. A regression testing tool should allow configuration to select test cases to be executed according to priority. This saves time as well as resource usage.
  • Identifies affected tests: If a regression testing tool is able to identify affected tests because of a change, it saves a lot of debugging and maintenance time that is otherwise spent by developers and automation testers to identify the affected tests after every change.
  • Easy to Maintain: Maintenance is an activity that takes the largest amount of time after test case creation for an automation tester. If a tool can save your maintenance time then go for it.
  • Schedule automated tests to run automatically: It is essential to be able to schedule automated test runs to be able to use the time when the team is not at the office. This adds to the team’s efficiency and productivity.
  • Detailed Reports to Determine Release Readiness: Before a release, it is essential to know the status of the release from all perspectives. This helps decide for the apt time for release. An automated testing tool that generates such reports can save a lot of time spent by Managers in gathering such statistics.
  • Allows collaboration: When test automation becomes a collaborative activity, quality becomes a team responsibility and activity. And, that is the goal of modern software development. If a tool encourages collaboration, that is the tool that can help you address quality from all perspectives.

Check our blog here for more details.

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FAQs on Regression Testing

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.

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