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.

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Importance of regression testing in software development

  • Regression testing is the major and important part of any software development as it checks the complete functionality after the newly added feature has been verified to be stable.

  • Regression testing verifies if the functionality is working as previously after the new changes are made to the software.

  • Agile methodology increases the risk visibility at an early stage of the project development life-cycle. Regression checks the stability of the system after new additions to it. So, the importance of regression testing in agile methodology for software development grows manifold.

  • Regression testing aims at performing continuous testing. Continuous testing helps in the overall quality and stability of the software.

  • As regression testing begins at an early stage it decreases the probability of missing the hidden requirements.

  • Finding and reporting a defect at an early stage of software development prevents excessive rework. This ultimately helps the testing team to meet the release timelines and deliver bug free software.

  • Regression testing is one of major factors in gaining customer confidence by living up to their expectations in terms of delivery and software quality. Organisations can showcase their ability in terms of efficient software delivery by adopting regression testing process in the test cycle.

  • Regression testing helps the team to identify the defects and eliminate them earlier in the software development life cycle. It eventually improves overall user experience for the developed software.

  • Regression testing ensures continuity of business functions with any rapid change in the software. Also since automated test cases saves the execution time, the testing team can focus on covering more areas of the software.

  • With the increasing demands for the quality of product, implementing automation regression testing in agile guarantees faster shipping of the product to the market.


The Problem With Manual Regression Testing

Let’s discuss the problems with regression testing :

  • The major issue with regression testing is the stringent timelines. With every change in the software, the testing team needs to ensure the existing functionality is not adversely affected in any sense. The regression test cases have to be executed repeatedly within the reduced regression cycles in sprint.

  • Optimizing the test cases in regression testing sometimes is difficult. As the scale of regression testing grows with every sprint, more number of automation test cases are difficult to maintain. It becomes necessary to accommodate these changes in the regression test cases.

  • Even with automation, regression testing involves running existing test cases multiple times. It takes a lot of time to complete the regression cycle. With every new additional feature, the number of times the amount of regression testing to be done only increases.

  • It might be difficult for someone new in the team to intervene halfway to understand what is being changed and what is being affected.

  • To perform smooth regression testing, the environment in which the testing is to be done has to be stable. Environmental issues while regression test execution can simply delay the execution process. If this happens on a regular interval we might also compromise on the concentration of testers to identify and report bugs.

  • Lack of communication between cross functional teams during regression testing also leads to problems.

  • Identifying the test cases in every module a change is made takes time, it is very likely that we miss to consider the test case which is critical to validate this change. It's very time consuming to figure out the test cases to be executed in the regression cycle. It is quite possible while choosing and selecting the test cases for execution, we might miss to check the critical functionality.

  • To perform smooth regression testing, the environment in which the testing is to be done has to be stable. Environmental issues while regression test execution can simply delay the execution process. If this happens on a regular interval we might also compromise on the concentration of testers to identify and report bugs.

  • Testing in the midst of code changes is not easy to implement and maintain.

  • The selection of the right automated tool also matters before we begin regression testing. Record and playback tools often don't work well in automated regression testing since it involves a lot of rework.

  • Regression tests need to be scripted and run on an automatic build environment. Automated regression tests need to be integrated within each sprint to work on the feedback continuously to address the defects as and when they are introduced to avoid late hardening sprints.

  • Regression tests need to be run after every development iteration and also after changes are made. There could be a lot of application stability or deployment issues observed during regression. This can slow down the overall testing.


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.


When to do Regression Testing?

Regression tests are typically run after changes have been made to the software, in order to ensure that the existing features still work as expected and that the changes have not introduced any new bugs or issues. They are also run periodically to ensure that the software remains stable over time.

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.



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.

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What Are The Risks In Manual Regression Testing ?

In order to achieve good automation regression testing results, the testing team needs to be proficient enough to possess good knowledge on the automation test techniques right from selection of tool and creation of automation test scripts to perform the test execution. Lack of automation expertise in the team can lead to a bad automated regression testing.

Let’s try to understand the risks associated in regression testing with an example :

  • Many times there is a customer who needs to rebuild an existing application built on a certain technology to a more advanced technology platform.

  • The developers will implement the functionality using the advanced technology and hand it over to the testing team for testing purposes.

  • There are chances that the testing team does not hold sufficient knowledge on the functionality of an application. In such a scenario there is high risk involved as the regression testing can go haywire due to lack of application insights. The regression risk grows exponentially as the application ages.

  • The regression risk grows exponentially as the application ages.

  • Even if the recent team did their best to understand the underlying design and structure , it’s very unlikely the changes they incorporated in the application fit with the original design theme.

  • After several years , the software is bound to be enhanced so many times by the team who were not involved in the original development.

  • The size of regression suite increases over time as the system grows in terms of functionality and complexity. Each new release faces the same constraints in terms of budget, schedule and team size. The complexity of the system is increased as more and more code is developed for new features and the interaction of various modules in the system increases.

  • These kinds of changes make the system grow more complex until it becomes brittle.

  • The system level dependencies are difficult to be understood by the team. As the team is uncertain on how to test the application, it ultimately results in insufficient test coverage of the system.

To be able to overcome these risks and challenges in regression testing, the team can come up with a risk based testing plan that helps to assess these challenges.

How to manage risk in regression testing ?

Agile teams are responsible to make incremental delivery which means as the number of iteration increases, the size of the product also increases significantly. Hence the risk of regression is proportional to the product. As the product size increases , the risk of regression as well increases.

The testing team needs to be prepared in advance to have a proper plan in place to mitigate the regression risk. Having extensive automated regression test suites can definitely help mitigate the risk. In every iteration the testing team needs to keep on updating the automation test scripts. The automated test cases can be stored in the configuration management tool so that it becomes easier to retrieve on need basis.

If the test cases history is available to the testing team, it benefits the team in troubleshooting any major problem. The testers at the beginning of the test execution can prepare a test strategy document specifying how the regression testing needs to be carried out. The testing team needs to review the tests written earlier in order to be able to add, update or delete any test script.

Post regression testing team can plan a sprint review with all the stakeholders and give a demo of the developed and tested application and further retrospect on improving the same based on the suggestions received. Certain prerequisites like generating test data, test data loading, build deployments can also be automated to minimize the risks.

Using a risk-based testing strategy will significantly reduce the regression risk that stands inherent in making small changes to a large system.

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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 consists of rules, predefined structures, and guidelines for automated test cases to follow. It is critical to have the system 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 a 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, applications having active development and maintenance for a long time are chosen for automation.
  • Automated tests should be easy to execute and 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 ongoing investment with zero returns.
  • Test cases should be executed across all the supported devices, machines, and screen resolutions to catch critical bugs before they reach the customer.
  • The automated testing tool should be such that it supports you in saving overall cost. Remember that training, hiring, and infrastructure cost money (and thus time)—and all these investments go into automation!
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Advantages Of Regression Testing

  • When the product's code base is huge and many test cases need to be executed, automated regression testing saves precious time, effort and resources that would otherwise be spent on manual testing.
  • Automated Regression Testing reports any errors quickly a few hours, which would otherwise take days if tested manually.
  • When done manually, it is highly possible for testers to miss or skip some test cases. This could be because they are new to the test functionality, or there is not enough time to complete the steps cycle, or due to genuine mistakes. All these factors are steered clear of in automation, ensuring no minor functionality is missed out.
  • To save time, manual testers may have to limit the test cases by executing the high-priority ones. In contrast, all the automated test cases can be run simultaneously multiple times, often after every single change; with no compromise in the test quality in every cycle.

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Disadvantages Of Regression Testing

  • Manual regression testing requires a lot of human effort and time and it becomes a complex process. If automation tool is not being used for regression testing then the testing process would be time consuming.

  • Regression testing has to be performed for every small change in the code as even a small portion of code can create issues in the software.

  • Regression testing needs to be done repeatedly each and every time in the agile sprint.

  • For complex functionalities we need to design huge test scripts which take a lot of time to execute. This might delay the test execution process and the testing team might fail to meet the delivery timelines.

  • In regression testing we aim to achieve maximum test coverage with the creation of limited test cases. This becomes difficult when we have stringent timelines

  • It becomes difficult for the testing team to determine the frequency of regression tests after every release and build of bug fixes.

  • It becomes difficult to track the test execution time when there are changes in business requirements that are communicated in between the sprint and are to be delivered on priority So the scrum teams need to be prepared to accept the late change in requirements.

  • Lack of understanding on the business requirements leads to improper creation of regression test suites. If we don't have proper regression test cases in place the testing team might miss on testing and reporting the critical functionality defect.

  • If the testing team does not understand the software development methodology they have adopted, there will be issues in planning the regression testing.

  • If the testing team does not understand the purpose of regression testing they follow wrong steps in the regression test execution process.

  • If the regression testing team does not possess adequate information on the application and the business requirements it will be difficult to perform a good regression testing.

  • If the testing team has done bad impact analysis or has no clarity on the changes in software it will be difficult to achieve good test coverage. This will eventually result in bad regression test execution.

  • It's a big challenge to perform regression testing under the time and resources constraints.


Types Of Regression Testing:

Regression testing is a crucial quality assurance practice in software development that involves retesting a portion of the application's existing functionality to ensure that recent code changes have not introduced new defects or broken existing features. There are several types of regression testing, each focusing on different aspects of the software. Here are some common types:

Corrective Regression Testing

This form of regression testing is utilized when no modifications are made to the product's specification. Moreover, the current test cases can be readily reused to perform the expected test.

Retest-all Regression Testing

Retest-all regression testing is a complicated form of testing. It demands all the system’s specifications should be verified from the origin. It reviews every minor change the software has experienced since its development. The most typical retest scenario occurs after other regression tests have failed to identify the source of the concern, as development teams reckon the issue happened far before the recent code modifications.

Selective Regression Testing

It is performed to identify how the code behaves when new code is added to the existing code. When this form of regression testing is performed, a subset from the current test cases is utilized to lower the effort and cost needed for retesting. For example, a test unit, like functions and variables, is re-run when an update is incorporated into the program.

Progressive Regression Testing

This type of regression testing yields more significant outputs when specific modifications are made in the program, and new test cases are developed. Performing this testing helps ensure that no elements in the prior version may be compromised in the latest and revised version.

Complete Regression Testing Complete Regression Testing:

This regression testing process is ideally used in case numerous updates are performed on the existing code. Additionally, full regression testing is used when the new updates to the source code have a distinct impact on the overall software. Conducting this type of testing is favorable in identifying unforeseen bugs. Once complete regression testing is concluded, the final software version can be made available to the user.

Partial Regression Testing Partial Regression Testing:

This software regression testing is conducted to validate the issues when a new code is pushed to an existing one. Partial regression testing ensures that a system functions as expected.

Unit Regression Testing

It is a crucial regression testing type primarily conducted in isolation and mainly focused on code units. All the dependencies and interactions are barred during unit regression testing.

The kind of regression testing chosen decides how the test cases for regression test cases are selected for execution. Also, read more about the iteration and complete regression testing in agile.


How to Improve the Effectiveness of Regression Testing

Improving the effectiveness of regression testing is crucial to maintaining the quality and stability of software products as they evolve. Here are several strategies to enhance the efficiency and effectiveness of regression testing:

Focus on fundamentals

Regression tests are often straightforward and affirmative.

In most cases, the tests are so uncomplicated they seem insignificant. However, such functions may be necessary to make the overall software perform as desired.

Create a restorable source

The ability to execute periodic regression tests is based on the availability of test data that may be repeated. Regression test data creation and management should be a part of the automation solution.

Govern the scope of testing

Initially, handling regression testing can be challenging. This is primarily because testers have to create, execute, and evaluate the regression tests in a limited time. A recommended way to go with regression testing is to identify the easy targets for regression testing as soon as possible.

Design efficient regression tests

Testers need to execute adequate test design strategies to achieve test case efficiency, which is purposed to achieve the most test scope from the minimum number of tests. These may be in the form of decision tables, pairwise test designs, and so on.

Aim for a repeatable strategy

Regression testing immensely relies on exact repeatability. This level of repeatability is achievable with a more comprehensive and highly repeatable testing procedure. When executing and resembling two regression tests of the same operation, the tests must be launched as similarly as possible. There may be deviations due to differences in a recent version, but the concept is to remain as constant as possible.

Use Automation Tools

Executing regression tests frequently at any substantial scale requires accuracy and precision. Manual regression testing is prone to errors. It’s easy to lose sight when managing redundant test cases accidentally. This is why automation is the advised method to accomplish effective regression testing.

Another key reason for choosing automated regression testing is its diverse scope of testing. In the absence of test automation , there is a risk of missing out on the quality goals of the software, leading to contrasts between test versions. Clearly, advanced automated tools, such as Testsigma, are the only way to sustain this effort.

Testsigma delivers a cloud-based test automation platform with all the necessary elements for effective automated regression testing. One of the critical features is that the tool suggests the relevant test cases after enhancements or bug fixes are performed on the software.

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Regression testing with Testsigma

Testsigma lets testers perform regression tests automatically and enhances the overall capabilities of regression tests with the following features:

  • Automates the regression tests using plain English.
  • AI generates regression test plans having all the simulated test cases.
  • The intelligent interface automatically defends or heals the regression tests in case of UI element changes.
  • Reduces the overall feedback time by conducting multiple tests simultaneously.
  • Provides steady integration to execute test cases after each new software build.
  • Generates test reports to ensure the release readiness of the software.

Critical benefits of Testsigma’s Automated Regression Testing

  • Identification of the concerned test cases: Adding new elements to the code may unintentionally impact parts of the code in other modules. This is primarily due to reliance on modules. Such regressions must be fixed within the sprint to ensure the bug does not move to the production-level code. Testsigma provides AI-driven attributes that automatically identify test cases that may be affected by such modifications.
  • Test case prioritization for faster testing: Testsigma prioritizes and segregates the test cases based on crucial modules, test case classifications, customer-reported bugs, and multiple other custom filters. This facilitates the creation of an optimized regression test plan.
  • Reduced feedback time with parallel regression tests: It may need significant time and resources to execute regression tests, including multiple test cases. Testsigma's parallel execution feature reduces the execution time extensively by trimming the feedback loop and allowing testers to find the bugs more quickly.
  • Automated Test Scheduling: Testsigma makes it possible to schedule test executions. This automates the regression testing process, making detecting regressions in the code more straightforward.
  • Comprehensive feedback reports: Testsigma delivers detailed feedback reports that help stakeholders identify failures and take action on the bugs. It offers exhaustive test reports that enable test results analysis in less time, more efficiently, and effectively. The tool delivers a pictorial representation of the passed and failed test cases, along with screenshots, videos, and detailed descriptions of each test step.

The kind of regression testing chosen decides how the test cases for regression test cases are selected for execution. Also, read more about the iteration and complete regression testing in agile.


Regression Testing: Techniques to look for

According to the type of project and its needs, different regression testing techniques can be adopted 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 is small, it can be manually managed in less time. However, if the number of regression test cases is significant, 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 created for stable features are added to the regression test suite. When automated, all the test cases in this suite can be executed after every change as the testing will be automated and the time taken would be less too.

Here are the steps to perform regression testing:

  • Identify the test cases: The first step is to identify the test cases that were executed in the previous testing cycle. These test cases should cover all the critical functionalities of the software application.

  • Determine the scope of testing: Determine which parts of the application will be tested in the regression testing phase. Depending on the size of the application and the changes made, the scope of testing can range from the entire application to just the affected areas.

  • Create test suites: Create a set of test suites that will be used to execute the identified test cases. Test suites are collections of test cases that are executed together as a group.

  • Prioritize test cases: Prioritize the test cases based on their importance and impact on the application. Test cases that cover the critical functionalities of the application should be given a higher priority.

  • Execute test cases: Execute the test cases in the selected test suites. During the execution, make sure to log any defects or issues that are found.

  • Analyze results: Analyze the test results to determine if any issues or defects were found. If issues or defects are found, document them and report them to the development team for resolution.

  • Report results: Report the results of the regression testing to the stakeholders, including any defects found and their severity. Provide recommendations on whether the application is ready for release or needs additional testing.

  • Repeat: Repeat the regression testing cycle as necessary for each subsequent release or update to the software application.

By following these steps, you can perform an effective regression testing process to ensure that your software application is functioning as intended and free from any regression defects.


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 lets you automate test cases in simple English with its "No Code" feature. Thus, it can be quickly learned and understood by non-technical members of the teams too, and can help jumpstart the automation of regression testing.

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Best Practices For Regression Testing

You can decide on the regression testing strategy considering the project type.

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.

Suppose the project is such that there won't be much time for regression testing at the end. In this case, 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

The following points will define the framework for regression testing:

  • 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 the desired results are:

  • If not after every change, regression testing should be performed at regular intervals.
  • The tester should test impacted areas for all the changes since the last regression test.
  • All the regression test cases should be up to date
  • One should consistently execute high-priority and critical test cases during a regression test
  • All the bugs caught while a regression test should be reported
  • Regression testing should be done to "minimize efforts" and "maximize results."

How Much Regression Testing Is Required?

There are two ways to find out:

  • Suppose all the test cases in the regression test suite are automated. This suite can be run from time to time, preferably after a certain number of changes. 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. Suppose the application is vast and has many test cases in the regression test suite. The decision to run all 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.

    After all the changes are included and tested functionally, execute this regression test suite and release it at once!

    Of course, this is not a solution if quick deployments need to be done after a few fixes.

  2. After 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 it can be considered complete.

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Regression Testing vs Functional Testing

While Regression Testing ensures no regressions in a product and 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 work on either end. It can include both functional testing and non-functional testing. Usually, the test cases created during functional testing 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 new modules are added or code changes are made. Sanity tests verify that the build is stable enough to perform subsequent stages of testing, such as end-to-end testing. When a build passes sanity testing, it is moved forward for further testing; if it fails, the build is denied further testing. It is also known as surface-level testing.

Regression testing determines whether code updates or modules have influenced the software's existing working functionalities/code. Regression testing is detailed testing which is a superset of sanity testing.

Feature Regression Testing Sanity Testing
Goal A 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 superset of 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 ensure that they operate independently as planned. Regression testing ensures that new code modifications do not interfere with the working code.

Feature Regression Testing Unit Testing
Goal To review the entire software is working as expected and new code changes have not affected the existing code. To review 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, the build is rejected, sent back to developers to fix, and no further testing activities are performed. As a result, it is often referred to as build-verification testing.

The primary 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 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 crucial for any product's success; hence, selecting proper regression test cases is imperative. The following points will help you pick relevant regression test cases.

  • When there are recent code changes in the Modules

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

  • Most error-prone modules

    Some modules are prone to bugs in an application and are fixed frequently. It is vital to keep those modules covered in regression testing.

  • Core functionalities of product

    The basic functionalities of the product should behave as expected, therefore testers should pick regression test cases 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 detrimental. Therefore, it is essential to include the integration tests and other complex test cases in the regression test suite.

  • Modules visible to the end-user

    No bug should be present on UI or client-facing modules, so testers should also pick regression test cases from such modules.

Here are 9 tips for selecting perfect regression test cases.


Must-have features for automated regression testing tool

  • Easy test authoring: The automated regression testing tool should simplify the creation and editing of tests. Because the number of regression test cases increases with the addition of a new feature and with each release. AI Driven Test Automation Software Tool Testsigma
  • Runs Automated Regression Tests after every build: The automated regression testing tool should allow regression tests to be run as frequently as needed. For this, the test execution should be quick and easy, and the tool should also support parallel test execution.
  • Quick Actionable Feedback: The feedback and reports provided by automated regression testing tool should indicate failures and action items to do next. This simplifies regression testing and working with feedback.
  • Saves time through Parallel execution: Time is everything in the software industry and will continue to be so as market competition intensifies. As a result, parallel execution becomes a crucial component for saving valuable test execution time.
  • Prioritizes the test cases for regression testing: Most of the time, execution of all test cases is not required after every change. A regression testing tool should be able to prioritize test cases for execution. This saves both time and resources.
  • Identifies affected tests: If a regression testing tool can identify affected tests as a result of a change, it saves developers and automation testers a lot of time debugging and maintaining the affected tests after each update.
  • Easy to Maintain: Maintenance is the most time-consuming task for an automation tester after creating a test case. If a tool can save you time on maintenance, just go for it!
  • Schedule automated tests to run automatically: You must be able to schedule automated test runs to use the time when the team is not in the office. This improves the team’s efficiency and productivity.
  • Detailed Reports to Determine Release Readiness: Before a product release, it is critical to understand the status of the release from all perspectives. This helps in determining the best timing for release. An automated testing tool that generates such reports can save Managers a significant amount of time obtaining such statistics.
  • Allows collaboration: Quality becomes a team responsibility when test automation becomes a collaborative activity. After all, that is the purpose of modern software development. If a tool supports collaboration, it is a tool that can assist you in addressing quality from all viewpoints.

If you are deciding on a simple but effective regression testing tool, give Testsigma a try!

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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.

During the SDLC (Software Development Life Cycle), features are added to a product incrementally. Once a feature has been thoroughly tested and declared stable, the test cases created for that feature are added to the regression test suite, which will be executed when future changes to the application are made.

Because the test cases in the regression test suite are stable, testers can easily automate them, and the process of automating them is known as regression testing automation.

It is possible to automate regression testing. To proceed with automation, ensure that the two conditions listed below are met:

  • The application under test is planned to be under active development for a long time.

  • The number of regression test cases for the application is quite large so manual execution will take a long time.

Even if all of the regression test cases are executed, much time will not be lost if the test cases are automated. In such a case, the amount of regression testing does not need to be considered.

However, if the test cases are not automated and time is an issue - which it usually is - the best way to proceed is to follow the steps below:

  • Analyze the change and the areas that have been impacted due to the change.

  • Execute high-priority test cases for the affected regions.

  • Perform the critical test scenarios for the application as a whole before any deployment or release.

Regression testing is vital for reducing the number of issues reported by customers after the release. However, there are times when managers and stakeholders fail to appreciate the importance of regression testing and thus don’t assign time for it.

As a tester, you can do the following things:

  • With each change testing, discuss the importance of regression testing with your management and project stakeholders - try to execute at least the highly important test cases for impacted areas.

  • Create a checklist before each release that includes the execution of the most important workflows a customer will go through.

  • Automate the regression test cases whenever possible.

Regression testing could be automated or performed manually depending on the processes used by an organization for a product. If the regression testing is automated, it will repeat the same steps.

However, if done manually, testers can use common sense to refrain from repeating the same steps for all test cases and instead try variations to uncover new bugs.

  • When the product's code base is enormous, and many test cases must be executed for regression testing, automation saves valuable time, effort, and resources spent on manual testing.

  • Automated Regression Testing detects and reports errors in hours, whereas manual testing could take days.

  • When done manually, humans may skip some test cases due to unfamiliarity with the functionality, a lack of time, or a genuine mistake. Automation ensures that no minor functionality is overlooked.

  • To save time, manual testers prioritize test cases for regression testing, whereas when automated, all automated test cases can be run any number of times, often after every single change. Thus, the quality is in check at every moment.

Regression Testing involves executing 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 a bug fix, enhancement, new feature, or 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. However, the end result of each iteration is a working deliverable. It is critical to perform regression testing before the end of each sprint to have a working deliverable at the end of each sprint.

This question has no right or wrong answer.

Some organizations place little emphasis on testing compared to deployment speed; thus, regression test automation is not always a part of DevOps. Other organizations have recognized the importance of regression testing in maintaining a product's overall quality and have incorporated it into their DevOps.

As people become more aware of the importance of maintaining the application's quality, experts advise businesses to incorporate regression test automation into DevOps to enhance the quality feedback loop.

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